TY - JOUR ID - citeulike:11530673 L3 - citeulike-article-id:11530673 TI - Mid-Pliocene climate modelled using the UK Hadley Centre Model: PlioMIP Experiments 1 and 2 JF - Geoscientific Model Development VL - 5 IS - 5 SP - 1109 EP - 1125 PB - Copernicus Publications N2 - The Pliocene Model Intercomparison Project (PlioMIP) is a sub-project of the Paleoclimate Modelling Intercomparison Project (PMIP) whose objective is to compare predictions of the mid-Pliocene climate from the widest possible range of general circulation models. The mid-Pliocene (3.3–3.0 Ma) is the most recent sustained period of greater warmth and atmospheric carbon dioxide concentration than the pre-industrial times and as such has potential to inform predictions of our warming climate in the coming century. This paper describes the UK contribution to PlioMIP using the Hadley Centre Model both in atmosphere-only mode (HadAM3, PlioMIP Experiment 1) and atmosphere-ocean coupled mode (HadCM3, PlioMIP Experiment 2). The coupled model predicts a greater overall warming (3.3 °C) relative to the control than the atmosphere-only (2.5 °C). The Northern Hemisphere latitudinal temperature gradient is greater in the coupled model with a warmer Equator and colder Arctic than the atmosphere-only model, which is constrained by sea surface temperatures from Pliocene proxy reconstructions. The atmosphere-only model predicts a reduction in equatorial precipitation and south Asian monsoon intensity, whereas the coupled model shows an increase in the intensity of these systems. We present sensitivity studies using alternative boundary conditions for both the Pliocene and the control simulations, indicating the sensitivity of the mid-Pliocene warming to uncertainties in both pre-industrial and mid-Pliocene climate. KW - hadcm_model KW - pliomip KW - pmip3 AU - Bragg, FJ AU - Lunt, DJ AU - Haywood, AM PY - 2012/09/13/ UR - http://dx.doi.org/10.5194/gmd-5-1109-2012 DO - doi: 10.5194/gmd-5-1109-2012 ER - TY - JOUR ID - citeulike:13651414 L3 - citeulike-article-id:13651414 TI - How well do simulated last glacial maximum tropical temperatures constrain equilibrium climate sensitivity? JF - Geophysical Research Letters VL - 42 IS - 13 SP - 5533 EP - 5539 SN - 00948276 N2 - Previous work demonstrated a significant correlation between tropical surface air temperature and equilibrium climate sensitivity (ECS) in PMIP (Paleoclimate Modelling Intercomparison Project) phase 2 model simulations of the last glacial maximum (LGM). This implies that reconstructed LGM cooling in this region could provide information about the climate system ECS value. We analyze results from new simulations of the LGM performed as part of Coupled Model Intercomparison Project (CMIP5) and PMIP phase 3. These results show no consistent relationship between the LGM tropical cooling and ECS. A radiative forcing and feedback analysis shows that a number of factors are responsible for this decoupling, some of which are related to vegetation and aerosol feedbacks. While several of the processes identified are LGM specific and do not impact on elevated CO2 simulations, this analysis demonstrates one area where the newer CMIP5 models behave in a qualitatively different manner compared with the older ensemble. The results imply that so-called Earth System components such as vegetation and aerosols can have a significant impact on the climate response in LGM simulations, and this should be taken into account in future analyses. KW - cmip5 KW - feedback KW - lgm KW - pmip2 KW - pmip3 KW - sensitivity KW - tropics AU - Hopcroft, Peter AU - Valdes, Paul PY - 2015/07/16/ UR - http://dx.doi.org/10.1002/2015gl064903 DO - doi: 10.1002/2015gl064903 ER - TY - JOUR ID - citeulike:14073809 L3 - citeulike-article-id:14073809 TI - What have we learnt from palaeoclimate simulations? JF - Journal of Quaternary Science VL - 31 IS - 4 SP - 363 EP - 385 SN - 02678179 N2 - There has been a gradual evolution in the way that palaeoclimate modelling and palaeoenvironmental data are used together to understand how the Earth System works, from an initial and largely descriptive phase through explicit hypothesis testing to diagnosis of underlying mechanisms. Analyses of past climate states are now regarded as integral to the evaluation of climate models, and have become part of the toolkit used to assess the likely realism of future projections. Palaeoclimate assessment has demonstrated that changes in large-scale features of climate that are governed by the energy and water balance show consistent responses to changes in forcing in different climate states, and these consistent responses are reproduced by climate models. However, state-of-the-art models are still largely unable to reproduce observed changes in climate at a regional scale reliably. While palaeoclimate analyses of state-of-the-art climate models suggest an urgent need for model improvement, much work is also needed on extending and improving palaeoclimate reconstructions and quantifying and reducing both numerical and interpretative uncertainties. KW - cmip5 KW - lgm KW - midholocene KW - model_data_comparison KW - pmip2 KW - pmip3 KW - reconstruction AU - Harrison, Sandy AU - Bartlein, Patrick AU - Prentice, Colin PY - 2016/05// UR - http://dx.doi.org/10.1002/jqs.2842 DO - doi: 10.1002/jqs.2842 ER - TY - JOUR ID - citeulike:9856296 L3 - citeulike-article-id:9856296 TI - Effects of Mountains and Ice Sheets on Global Ocean Circulation* T2 - Journal of Climate JF - J. Climate VL - 24 IS - 11 SP - 2814 EP - 2829 PB - American Meteorological Society N2 - The impact of mountains and ice sheets on the large-scale circulation of the world?s oceans is investigated in a series of simulations with a new coupled ocean?atmosphere model [Oregon State University?University of Victoria model (OSUVic)], in which the height of orography is scaled from 1.5 times the actual height (at T42 resolution) to 0 (no mountains). The results suggest that the effects of mountains and ice sheets on the buoyancy and momentum transfer from the atmosphere to the surface ocean determine the present pattern of deep ocean circulation. Higher mountains reduce water vapor transport from the Pacific and Indian Oceans into the Atlantic Ocean and contribute to increased (decreased) salinities and enhanced (reduced) deep-water formation and meridional overturning circulation in the Atlantic (Pacific). Orographic effects also lead to the observed interhemispheric asymmetry of midlatitude zonal wind stress. The presence of the Antarctic ice sheet cools winter air temperatures by more than 20°C directly above the ice sheet and sets up a polar meridional overturning cell in the atmosphere. The resulting increased meridional temperature gradient strengthens midlatitude westerlies by ~25% and shifts them poleward by ~10°. This leads to enhanced and poleward-shifted upwelling of deep waters in the Southern Ocean, a stronger Antarctic Circumpolar Current, increased poleward atmospheric moisture transport, and more advection of high-salinity Indian Ocean water into the South Atlantic. Thus, it is the current configuration of mountains and ice sheets on earth that determines the difference in deep-water formation between the Atlantic and the Pacific. AbstractThe impact of mountains and ice sheets on the large-scale circulation of the world?s oceans is investigated in a series of simulations with a new coupled ocean?atmosphere model [Oregon State University?University of Victoria model (OSUVic)], in which the height of orography is scaled from 1.5 times the actual height (at T42 resolution) to 0 (no mountains). The results suggest that the effects of mountains and ice sheets on the buoyancy and momentum transfer from the atmosphere to the surface ocean determine the present pattern of deep ocean circulation. Higher mountains reduce water vapor transport from the Pacific and Indian Oceans into the Atlantic Ocean and contribute to increased (decreased) salinities and enhanced (reduced) deep-water formation and meridional overturning circulation in the Atlantic (Pacific). Orographic effects also lead to the observed interhemispheric asymmetry of midlatitude zonal wind stress. The presence of the Antarctic ice sheet cools winter air temperatures by more than 20°C directly above the ice sheet and sets up a polar meridional overturning cell in the atmosphere. The resulting increased meridional temperature gradient strengthens midlatitude westerlies by ~25% and shifts them poleward by ~10°. This leads to enhanced and poleward-shifted upwelling of deep waters in the Southern Ocean, a stronger Antarctic Circumpolar Current, increased poleward atmospheric moisture transport, and more advection of high-salinity Indian Ocean water into the South Atlantic. Thus, it is the current configuration of mountains and ice sheets on earth that determines the difference in deep-water formation between the Atlantic and the Pacific. KW - osuvic_model KW - pmip3 AU - Schmittner, Andreas AU - Silva, Tiago AU - Fraedrich, Klaus AU - Kirk, Edilbert AU - Lunkeit, Frank PY - 2011/12/20/ UR - http://dx.doi.org/10.1175/2010jcli3982.1 DO - doi: 10.1175/2010jcli3982.1 ER - TY - JOUR ID - citeulike:13884547 L3 - citeulike-article-id:13884547 TI - Continental-scale temperature variability in PMIP3 simulations and PAGES 2k regional temperature reconstructions over the past millennium JF - Climate of the Past VL - 11 IS - 12 SP - 1673 EP - 1699 PB - Copernicus Publications N2 - Estimated external radiative forcings, model results, and proxy-based climate reconstructions have been used over the past several decades to improve our understanding of the mechanisms underlying observed climate variability and change over the past millennium. Here, the recent set of temperature reconstructions at the continental-scale generated by the PAGES 2k project and a collection of state-of-the-art model simulations driven by realistic external forcings are jointly analysed. The first aim is to estimate the consistency between model results and reconstructions for each continental-scale region over the time and frequency domains. Secondly, the links between regions are investigated to determine whether reconstructed global-scale covariability patterns are similar to those identified in model simulations. The third aim is to assess the role of external forcings in the observed temperature variations. From a large set of analyses, we conclude that models are in relatively good agreement with temperature reconstructions for Northern Hemisphere regions, particularly in the Arctic. This is likely due to the relatively large amplitude of the externally forced response across northern and high-latitude regions, which results in a clearly detectable signature in both reconstructions and simulations. Conversely, models disagree strongly with the reconstructions in the Southern Hemisphere. Furthermore, the simulations are more regionally coherent than the reconstructions, perhaps due to an underestimation of the magnitude of internal variability in models or to an overestimation of the response to the external forcing in the Southern Hemisphere. Part of the disagreement might also reflect large uncertainties in the reconstructions, specifically in some Southern Hemisphere regions, which are based on fewer palaeoclimate records than in the Northern Hemisphere. KW - cmip5 KW - model_data_comparison KW - past1000 KW - pmip3 KW - reconstruction AU - PAGES 2k-PMIP3 group PY - 2015/12/16/ UR - http://dx.doi.org/10.5194/cp-11-1673-2015 DO - doi: 10.5194/cp-11-1673-2015 ER - TY - JOUR ID - citeulike:13822889 L3 - citeulike-article-id:13822889 TI - Glacial Atlantic overturning increased by wind stress in climate models JF - Geophysical Research Letters VL - 42 IS - 22 SP - 9862 EP - 9868 SN - 00948276 N2 - Previous Paleoclimate Model Intercomparison Project (PMIP) simulations of the Last Glacial Maximum (LGM) Atlantic Meridional Overturning Circulation (AMOC) showed dissimilar results on transports and structure. Here we analyze the most recent PMIP3 models, which show a consistent increase (on average by 41 ± 26%) and deepening (663 ± 550 m) of the AMOC with respect to pre-industrial simulations, in contrast to some reconstructions from proxy data. Simulations run with the University of Victoria (UVic) ocean circulation model suggest that this is caused by changes in the Northern Hemisphere wind stress, brought about by the presence of ice sheets over North America in the LGM. When forced with LGM wind stress anomalies from PMIP3 models, the UVic model responds with an increase of the northward salt transport in the North Atlantic, which strengthens North Atlantic Deep Water formation and the AMOC. These results improve our understanding of the LGM AMOC's driving forces, and suggest that some ocean mechanisms may not be correctly represented in PMIP3 models, or some proxy data may need reinterpretation. KW - amoc KW - cmip5 KW - lgm KW - pmip3 AU - Muglia, Juan AU - Schmittner, Andreas PY - 2015/11/19/ UR - http://dx.doi.org/10.1002/2015gl064583 DO - doi: 10.1002/2015gl064583 ER - TY - JOUR ID - citeulike:13883938 L3 - citeulike-article-id:13883938 TI - Links between tropical Pacific seasonal, interannual and orbital variability during the Holocene JF - Nature Geoscience VL - advance online publication PB - Nature Publishing Group SN - 1752-0894 KW - cmip5 KW - enso KW - midholocene KW - model_data_comparison KW - pmip3 AU - Emile-Geay, J AU - Cobb, KM AU - Carré, M AU - Braconnot, P AU - Leloup, J AU - Zhou, Y AU - Harrison, SP AU - Corrège, T AU - McGregor, HV AU - Collins, M AU - Driscoll, R AU - Elliot, M AU - Schneider, B AU - Tudhope, A PY - 2015/12/14/ UR - http://dx.doi.org/10.1038/ngeo2608 DO - doi: 10.1038/ngeo2608 ER - TY - JOUR ID - citeulike:13848014 L3 - citeulike-article-id:13848014 TI - A model–data comparison for a multi-model ensemble of early Eocene atmosphere–ocean simulations: EoMIP JF - Climate of the Past VL - 8 IS - 5 SP - 1717 EP - 1736 PB - Copernicus Publications N2 - The early Eocene (~55 to 50 Ma) is a time period which has been explored in a large number of modelling and data studies. Here, using an ensemble of previously published model results, making up "EoMIP" – the Eocene Modelling Intercomparison Project – and syntheses of early Eocene terrestrial and sea surface temperature data, we present a self-consistent inter-model and model–data comparison. This shows that the previous modelling studies exhibit a very wide inter-model variability, but that at high CO2, there is good agreement between models and data for this period, particularly if possible seasonal biases in some of the proxies are considered. An energy balance analysis explores the reasons for the differences between the model results, and suggests that differences in surface albedo feedbacks, water vapour and lapse rate feedbacks, and prescribed aerosol loading are the dominant cause for the different results seen in the models, rather than inconsistencies in other prescribed boundary conditions or differences in cloud feedbacks. The CO2 level which would give optimal early Eocene model–data agreement, based on those models which have carried out simulations with more than one CO2 level, is in the range of 2500 ppmv to 6500 ppmv. Given the spread of model results, tighter bounds on proxy estimates of atmospheric CO2 and temperature during this time period will allow a quantitative assessment of the skill of the models at simulating warm climates. If it is the case that a model which gives a good simulation of the Eocene will also give a good simulation of the future, then such an assessment could be used to produce metrics for weighting future climate predictions. KW - model_data_comparison KW - pmip3 AU - Lunt, DJ AU - Jones, Dunkley AU - Heinemann, M AU - Huber, M AU - LeGrande, A AU - Winguth, A AU - Loptson, C AU - Marotzke, J AU - Roberts, CD AU - Tindall, J AU - Valdes, P AU - Winguth, C PY - 2012/10/29/ UR - http://dx.doi.org/10.5194/cp-8-1717-2012 DO - doi: 10.5194/cp-8-1717-2012 ER - TY - JOUR ID - citeulike:12963856 L3 - citeulike-article-id:12963856 TI - A model–data comparison of the Holocene global sea surface temperature evolution JF - Climate of the Past VL - 9 IS - 4 SP - 1807 EP - 1839 PB - Copernicus Publications N2 - We compare the ocean temperature evolution of the Holocene as simulated by climate models and reconstructed from marine temperature proxies. We use transient simulations from a coupled atmosphere–ocean general circulation model, as well as an ensemble of time slice simulations from the Paleoclimate Modelling Intercomparison Project. The general pattern of sea surface temperature (SST) in the models shows a high-latitude cooling and a low-latitude warming. The proxy dataset comprises a global compilation of marine alkenone- and Mg/Ca-derived SST estimates. Independently of the choice of the climate model, we observe significant mismatches between modelled and estimated SST amplitudes in the trends for the last 6000 yr. Alkenone-based SST records show a similar pattern as the simulated annual mean SSTs, but the simulated SST trends underestimate the alkenone-based SST trends by a factor of two to five. For Mg/Ca, no significant relationship between model simulations and proxy reconstructions can be detected. We test if such discrepancies can be caused by too simplistic interpretations of the proxy data. We explore whether consideration of different growing seasons and depth habitats of the planktonic organisms used for temperature reconstruction could lead to a better agreement of model results with proxy data on a regional scale. The extent to which temporal shifts in growing season or vertical shifts in depth habitat can reduce model–data misfits is determined. We find that invoking shifts in the living season and habitat depth can remove some of the model–data discrepancies in SST trends. Regardless whether such adjustments in the environmental parameters during the Holocene are realistic, they indicate that when modelled temperature trends are set up to allow drastic shifts in the ecological behaviour of planktonic organisms, they do not capture the full range of reconstructed SST trends. Results indicate that modelled and reconstructed temperature trends are to a large degree only qualitatively comparable, thus providing a challenge for the interpretation of proxy data as well as the model sensitivity to orbital forcing. KW - cmip5 KW - midholocene KW - model_data_comparison KW - pmip2 KW - pmip3 KW - sst AU - Lohmann, G AU - Pfeiffer, M AU - Laepple, T AU - Leduc, G AU - Kim, JH PY - 2013/08/06/ UR - http://dx.doi.org/10.5194/cp-9-1807-2013 DO - doi: 10.5194/cp-9-1807-2013 ER - TY - JOUR ID - citeulike:9505383 L3 - citeulike-article-id:9505383 TI - The HadGEM2-ES implementation of CMIP5 centennial simulations JF - Geoscientific Model Development VL - 4 IS - 3 SP - 543 EP - 570 PB - Copernicus Publications N2 - The scientific understanding of the Earth's climate system, including the central question of how the climate system is likely to respond to human-induced perturbations, is comprehensively captured in GCMs and Earth System Models (ESM). Diagnosing the simulated climate response, and comparing responses across different models, is crucially dependent on transparent assumptions of how the GCM/ESM has been driven – especially because the implementation can involve subjective decisions and may differ between modelling groups performing the same experiment. This paper outlines the climate forcings and setup of the Met Office Hadley Centre ESM, HadGEM2-ES for the CMIP5 set of centennial experiments. We document the prescribed greenhouse gas concentrations, aerosol precursors, stratospheric and tropospheric ozone assumptions, as well as implementation of land-use change and natural forcings for the HadGEM2-ES historical and future experiments following the Representative Concentration Pathways. In addition, we provide details of how HadGEM2-ES ensemble members were initialised from the control run and how the palaeoclimate and AMIP experiments, as well as the "emission-driven" RCP experiments were performed. KW - cmip5 KW - hadgem_model KW - pmip3 AU - Jones, CD AU - Hughes, JK AU - Bellouin, N AU - Hardiman, SC AU - Jones, GS AU - Knight, J AU - Liddicoat, S AU - O'Connor, FM AU - Andres, RJ AU - Bell, C AU - Boo, KO AU - Bozzo, A AU - Butchart, N AU - Cadule, P AU - Corbin, KD AU - Doutriaux-Boucher, M AU - Friedlingstein, P AU - Gornall, J AU - Gray, L AU - Halloran, PR AU - Hurtt, G AU - Ingram, WJ AU - Lamarque, JF AU - Law, RM AU - Meinshausen, M AU - Osprey, S AU - Palin, EJ AU - Chini, Parsons AU - Raddatz, T AU - Sanderson, MG AU - Sellar, AA AU - Schurer, A AU - Valdes, P AU - Wood, N AU - Woodward, S AU - Yoshioka, M AU - Zerroukat, M PY - 2011/07/01/ UR - http://dx.doi.org/10.5194/gmd-4-543-2011 DO - doi: 10.5194/gmd-4-543-2011 ER - TY - JOUR ID - citeulike:13429851 L3 - citeulike-article-id:13429851 TI - A New Global Climate Model of the Meteorological Research Institute: MRI-CGCM3 - Model Description and Basic Performance - JF - Journal of the Meteorological Society of Japan VL - 90A IS - 0 SP - 23 EP - 64 SN - 0026-1165 KW - cmip5 KW - mri_model KW - pmip3 AU - Yukimoto, Seiji AU - Adachi, Yukimasa AU - Hosaka, Masahiro AU - Sakami, Tomonori AU - Yoshimura, Hiromasa AU - Hirabara, Mikitoshi AU - Tanaka, Taichu AU - Shindo, Eiki AU - Tsujino, Hiroyuki AU - Deushi, Makoto AU - Mizuta, Ryo AU - Yabu, Shoukichi AU - Obata, Atsushi AU - Nakano, Hideyuki AU - Koshiro, Tsuyoshi AU - Ose, Tomoaki AU - Kitoh, Akio PY - 2012/// UR - http://dx.doi.org/10.2151/jmsj.2012-a02 DO - doi: 10.2151/jmsj.2012-a02 ER - TY - RPRT ID - citeulike:13848000 L3 - citeulike-article-id:13848000 TI - Meteorological Research Institute-Earth System Model Version 1 (MRI-ESM1) — Model Description — KW - cmip5 KW - mri_model KW - pmip3 AU - Yukimoto, Seiji AU - Yoshimura, Hiromasa AU - Hosaka, Masahiro AU - Sakami, Tomonori AU - Tsujino, Hiroyuki AU - Hirabara, Mikitoshi AU - Tanaka, Taichu AU - Deushi, Makoto AU - Obata, Atsushi AU - Nakano, Hideyuki AU - Adachi, Yukimasa AU - Shindo, Eiki AU - Yabu, Shoukichi AU - Ose, Tomoaki AU - Kitoh, Akio UR - http://www.mri-jma.go.jp/Publish/Technical/DATA/VOL_64/tec_rep_mri_64.pdf ER - TY - JOUR ID - citeulike:13847988 L3 - citeulike-article-id:13847988 TI - Aerosol- and greenhouse gas-induced changes in summer rainfall and circulation in the Australasian region: a study using single-forcing climate simulations JF - Atmospheric Chemistry and Physics VL - 12 IS - 14 SP - 6377 EP - 6404 PB - Copernicus Publications N2 - We use a coupled atmosphere-ocean global climate model (CSIRO-Mk3.6) to investigate the drivers of trends in summer rainfall and circulation in the vicinity of northern Australia. As part of the Coupled Model Intercomparison Project Phase 5 (CMIP5), we perform a 10-member 21st century ensemble driven by Representative Concentration Pathway 4.5 (RCP4.5). To investigate the roles of different forcing agents, we also perform multiple 10-member ensembles of historical climate change, which are analysed for the period 1951–2010. The historical runs include ensembles driven by "all forcings" (HIST), all forcings except anthropogenic aerosols (NO_AA) and forcing only from long-lived greenhouse gases (GHGAS). Anthropogenic aerosol-induced effects in a warming climate are calculated from the difference of HIST minus NO_AA.

CSIRO-Mk3.6 simulates a strong summer rainfall decrease over north-western Australia (NWA) in RCP4.5, whereas simulated trends in HIST are weakly positive (but insignificant) during 1951–2010. The weak rainfall trends in HIST are due to compensating effects of different forcing agents: there is a significant decrease in GHGAS, offset by an aerosol-induced increase.

Observations show a significant increase of summer rainfall over NWA during the last few decades. The large magnitude of the observed NWA rainfall trend is not captured by 440 unforced 60-yr trends calculated from a 500-yr pre-industrial control run, even though the model's decadal variability appears to be realistic. This suggests that the observed trend includes a forced component, despite the fact that the model does not simulate the magnitude of the observed rainfall increase in response to "all forcings" (HIST).

We investigate the mechanism of simulated and observed NWA rainfall changes by exploring changes in circulation over the Indo-Pacific region. The key circulation feature associated with the rainfall increase in reanalyses is a lower-tropospheric cyclonic circulation trend off the coast of NWA, which enhances the monsoonal flow. The model shows an aerosol-induced cyclonic circulation trend off the coast of NWA in HIST minus NO_AA, whereas GHGAS shows an anticyclonic circulation trend. This explains why the aerosol-induced effect is an increase of rainfall over NWA, and the greenhouse gas-induced effect is of opposite sign.

Possible explanations for the cyclonic (anticyclonic) circulation trend in HIST minus NO_AA (GHGAS) involve changes in the Walker circulation or the local Hadley circulation. In either case, a plausible atmospheric mechanism is that the circulation anomaly is a Rossby wave response to convective heating anomalies south of the Equator. We also discuss the possible role of air-sea interactions, e.g. an increase (decrease) of sea-surface temperatures off the coast of NWA in HIST minus NO_AA (GHGAS). Further research is needed to better understand the mechanisms and the extent to which these are model-dependent.

In summary, our results suggest that anthropogenic aerosols may have "masked" greenhouse gas-induced changes in rainfall over NWA and in circulation over the wider Indo-Pacific region. Due to the opposing effects of greenhouse gases and anthropogenic aerosols, future trends may be very different from trends observed over the last few decades. KW - cmip5 KW - csiro_model KW - pmip3 KW - rcp45 AU - Rotstayn, LD AU - Jeffrey, SJ AU - Collier, MA AU - Dravitzki, SM AU - Hirst, AC AU - Syktus, JI AU - Wong, KK PY - 2012/07/23/ UR - http://dx.doi.org/10.5194/acp-12-6377-2012 DO - doi: 10.5194/acp-12-6377-2012 ER - TY - JOUR ID - citeulike:13847986 L3 - citeulike-article-id:13847986 TI - Australia’s CMIP5 submission using the CSIRO-Mk3.6 model JF - Australian Meteorological and Oceanographic Journal VL - 63 IS - 1 SP - 1 EP - 13 N2 - A comprehensive set of climate modelling experiments has been performed to provide input into the Coupled Model Intercomparison Project – phase 5 (CMIP5). The CSIRO-Mk3.6 climate model was used to prepare a joint CMIP5 submission under a partnership between the Commonwealth Scientific and Industrial Re - search Organisation (CSIRO) and the Queensland Climate Change Centre of Ex - cellence (QCCCE). The submission includes data for 163 variables from 22 experi - ments. The raw model output has been post-processed into CMIP5 format using the Climate Model Output Rewriter and publicly released on the Earth System Grid. The Mk3.6 submission includes data for most of the Core, Tier 1 and Tier 2 CMIP5 longer-term experiments which don’t require modelling of the carbon cycle. Data have been provided for nine historical experiments driven by a range of forcings to support detection and attribution studies. Most experiments have been performed as an ensemble of runs, with ensemble sizes exceeding CMIP5 recommendations. KW - 1pctco2 KW - abrupt4xco2 KW - cmip5 KW - csiro_model KW - midholocene KW - picontrol KW - pmip3 AU - Jeffrey, Stephen AU - Rotstayn, Leon AU - Collier, Mark AU - Dravitski, Stacey AU - Hamalainen, Carlo AU - Moeseneder, Chris AU - Wong, Kenneth AU - Syktus, Jozef PY - 2013/// UR - http://www.bom.gov.au/amoj/docs/2013/jeffrey_hres.pdf ER - TY - JOUR ID - citeulike:12176562 L3 - citeulike-article-id:12176562 TI - Paleoclimate Data–Model Comparison and the Role of Climate Forcings over the Past 1500 Years* T2 - Journal of Climate JF - J. Climate VL - 26 IS - 18 SP - 6915 EP - 6936 PB - American Meteorological Society N2 - AbstractThe past 1500 years provide a valuable opportunity to study the response of the climate system to external forcings. However, the integration of paleoclimate proxies with climate modeling is critical to improving the understanding of climate dynamics. In this paper, a climate system model and proxy records are therefore used to study the role of natural and anthropogenic forcings in driving the global climate. The inverse and forward approaches to paleoclimate data?model comparison are applied, and sources of uncertainty are identified and discussed. In the first of two case studies, the climate model simulations are compared with multiproxy temperature reconstructions. Robust solar and volcanic signals are detected in Southern Hemisphere temperatures, with a possible volcanic signal detected in the Northern Hemisphere. The anthropogenic signal dominates during the industrial period. It is also found that seasonal and geographical biases may cause multiproxy reconstructions to overestimate the magnitude of the long-term preindustrial cooling trend. In the second case study, the model simulations are compared with a coral δ18O record from the central Pacific Ocean. It is found that greenhouse gases, solar irradiance, and volcanic eruptions all influence the mean state of the central Pacific, but there is no evidence that natural or anthropogenic forcings have any systematic impact on El Niño?Southern Oscillation. The proxy climate relationship is found to change over time, challenging the assumption of stationarity that underlies the interpretation of paleoclimate proxies. These case studies demonstrate the value of paleoclimate data?model comparison but also highlight the limitations of current techniques and demonstrate the need to develop alternative approaches. KW - csiro_model KW - model_data_comparison KW - past1000 KW - pmip3 AU - Phipps, Steven AU - McGregor, Helen AU - Gergis, Joëlle AU - Gallant, Ailie AU - Neukom, Raphael AU - Stevenson, Samantha AU - Ackerley, Duncan AU - Brown, Josephine AU - Fischer, Matt AU - van Ommen, Tas PY - 2013/03/18/ UR - http://dx.doi.org/10.1175/jcli-d-12-00108.1 DO - doi: 10.1175/jcli-d-12-00108.1 ER - TY - JOUR ID - citeulike:10786612 L3 - citeulike-article-id:10786612 TI - The CSIRO Mk3L climate system model version 1.0 – Part 2: Response to external forcings JF - Geoscientific Model Development VL - 5 IS - 3 SP - 649 EP - 682 PB - Copernicus Publications N2 - The CSIRO Mk3L climate system model is a coupled general circulation model, designed primarily for millennial-scale climate simulation and palaeoclimate research. Mk3L includes components which describe the atmosphere, ocean, sea ice and land surface, and combines computational efficiency with a stable and realistic control climatology. It is freely available to the research community. This paper evaluates the response of the model to external forcings which correspond to past and future changes in the climate system.

A simulation of the mid-Holocene climate is performed, in which changes in the seasonal and meridional distribution of incoming solar radiation are imposed. Mk3L correctly simulates increased summer temperatures at northern mid-latitudes and cooling in the tropics. However, it is unable to capture some of the regional-scale features of the mid-Holocene climate, with the precipitation over Northern Africa being deficient. The model simulates a reduction of between 7 and 15% in the amplitude of El Niño-Southern Oscillation, a smaller decrease than that implied by the palaeoclimate record. However, the realism of the simulated ENSO is limited by the model's relatively coarse spatial resolution.

Transient simulations of the late Holocene climate are then performed. The evolving distribution of insolation is imposed, and an acceleration technique is applied and assessed. The model successfully captures the temperature changes in each hemisphere and the upward trend in ENSO variability. However, the lack of a dynamic vegetation scheme does not allow it to simulate an abrupt desertification of the Sahara.

To assess the response of Mk3L to other forcings, transient simulations of the last millennium are performed. Changes in solar irradiance, atmospheric greenhouse gas concentrations and volcanic emissions are applied to the model. The model is again broadly successful at simulating larger-scale changes in the climate system. Both the magnitude and the spatial pattern of the simulated 20th century warming are consistent with observations. However, the model underestimates the magnitude of the relative warmth associated with the Mediaeval Climate Anomaly.

Finally, three transient simulations are performed, in which the atmospheric CO2 concentration is stabilised at two, three and four times the pre-industrial value. All three simulations exhibit ongoing surface warming, reduced sea ice cover, and a reduction in the rate of North Atlantic Deep Water formation followed by its gradual recovery. Antarctic Bottom Water formation ceases, with the shutdown being permanent for a trebling and quadrupling of the CO2 concentration. The transient and equilibrium climate sensitivities of the model are determined. The short-term transient response to a doubling of the CO2 concentration at 1% per year is a warming of 1.59 ± 0.08 K, while the long-term equilibrium response is a warming of at least 3.85 ± 0.02 K. KW - csiro_model KW - midholocene KW - past1000 KW - pmip3 AU - Phipps, SJ AU - Rotstayn, LD AU - Gordon, HB AU - Roberts, JL AU - Hirst, AC AU - Budd, WF PY - 2012/05/14/ UR - http://dx.doi.org/10.5194/gmd-5-649-2012 DO - doi: 10.5194/gmd-5-649-2012 ER - TY - JOUR ID - citeulike:13847941 L3 - citeulike-article-id:13847941 TI - The CSIRO Mk3L climate system model version 1.0 – Part 1: Description and evaluation JF - Geoscientific Model Development VL - 4 IS - 2 SP - 483 EP - 509 PB - Copernicus Publications N2 - The CSIRO Mk3L climate system model is a coupled general circulation model, designed primarily for millennial-scale climate simulations and palaeoclimate research. Mk3L includes components which describe the atmosphere, ocean, sea ice and land surface, and combines computational efficiency with a stable and realistic control climatology. This paper describes the model physics and software, analyses the control climatology, and evaluates the ability of the model to simulate the modern climate.

Mk3L incorporates a spectral atmospheric general circulation model, a z-coordinate ocean general circulation model, a dynamic-thermodynamic sea ice model and a land surface scheme with static vegetation. The source code is highly portable, and has no dependence upon proprietary software. The model distribution is freely available to the research community. A 1000-yr climate simulation can be completed in around one-and-a-half months on a typical desktop computer, with greater throughput being possible on high-performance computing facilities.

Mk3L produces realistic simulations of the larger-scale features of the modern climate, although with some biases on the regional scale. The model also produces reasonable representations of the leading modes of internal climate variability in both the tropics and extratropics. The control state of the model exhibits a high degree of stability, with only a weak cooling trend on millennial timescales. Ongoing development work aims to improve the model climatology and transform Mk3L into a comprehensive earth system model. KW - csiro_model KW - pmip3 AU - Phipps, SJ AU - Rotstayn, LD AU - Gordon, HB AU - Roberts, JL AU - Hirst, AC AU - Budd, WF PY - 2011/06/17/ UR - http://dx.doi.org/10.5194/gmd-4-483-2011 DO - doi: 10.5194/gmd-4-483-2011 ER - TY - JOUR ID - citeulike:13847937 L3 - citeulike-article-id:13847937 TI - Modelling mid-Pliocene climate with COSMOS JF - Geoscientific Model Development VL - 5 IS - 5 SP - 1221 EP - 1243 PB - Copernicus Publications N2 - In this manuscript we describe the experimental procedure employed at the Alfred Wegener Institute in Germany in the preparation of the simulations for the Pliocene Model Intercomparison Project (PlioMIP). We present a description of the utilized Community Earth System Models (COSMOS, version: COSMOS-landveg r2413, 2009) and document the procedures that we applied to transfer the Pliocene Research, Interpretation and Synoptic Mapping (PRISM) Project mid-Pliocene reconstruction into model forcing fields. The model setup and spin-up procedure are described for both the paleo- and preindustrial (PI) time slices of PlioMIP experiments 1 and 2, and general results that depict the performance of our model setup for mid-Pliocene conditions are presented. The mid-Pliocene, as simulated with our COSMOS setup and PRISM boundary conditions, is both warmer and wetter in the global mean than the PI. The globally averaged annual mean surface air temperature in the mid-Pliocene standalone atmosphere (fully coupled atmosphere-ocean) simulation is 17.35 °C (17.82 °C), which implies a warming of 2.23 °C (3.40 °C) relative to the respective PI control simulation. KW - cosmos_model KW - midpliocene KW - pliomip KW - pmip3 AU - Stepanek, C AU - Lohmann, G PY - 2012/10/05/ UR - http://dx.doi.org/10.5194/gmd-5-1221-2012 DO - doi: 10.5194/gmd-5-1221-2012 ER - TY - JOUR ID - citeulike:12722232 L3 - citeulike-article-id:12722232 TI - Different ocean states and transient characteristics in Last Glacial Maximum simulations and implications for deglaciation JF - Climate of the Past VL - 9 IS - 5 SP - 2319 EP - 2333 PB - Copernicus Publications N2 - The last deglaciation is one of the best constrained global-scale climate changes documented by climate archives. Nevertheless, understanding of the underlying dynamics is still limited, especially with respect to abrupt climate shifts and associated changes in the Atlantic meridional overturning circulation (AMOC) during glacial and deglacial periods. A fundamental issue is how to obtain an appropriate climate state at the Last Glacial Maximum (LGM, 21 000 yr before present, 21 ka BP) that can be used as an initial condition for deglaciation. With the aid of a comprehensive climate model, we found that initial ocean states play an important role on the equilibrium timescale of the simulated glacial ocean. Independent of the initialization, the climatological surface characteristics are similar and quasi-stationary, even when trends in the deep ocean are still significant, which provides an explanation for the large spread of simulated LGM ocean states among the Paleoclimate Modeling Intercomparison Project phase 2 (PMIP2) models. Accordingly, we emphasize that caution must be taken when alleged quasi-stationary states, inferred on the basis of surface properties, are used as a reference for both model inter-comparison and data model comparison.

The simulated ocean state with the most realistic AMOC is characterized by a pronounced vertical stratification, in line with reconstructions. Hosing experiments further suggest that the response of the glacial ocean is dependent on the ocean background state, i.e. only the state with robust stratification shows an overshoot behavior in the North Atlantic. We propose that the salinity stratification represents a key control on the AMOC pattern and its transient response to perturbations. Furthermore, additional experiments suggest that the stratified deep ocean formed prior to the LGM during a time of minimum obliquity (~ 27 ka BP). This indicates that changes in the glacial deep ocean already occur before the last deglaciation. In combination, these findings represent a new paradigm for the LGM and the last deglaciation, which challenges the conventional evaluation of glacial and deglacial AMOC changes based on an ocean state derived from 21 ka BP boundary conditions. KW - cosmos_model KW - lgm KW - pmip2 KW - pmip3 AU - Zhang, X AU - Lohmann, G AU - Knorr, G AU - Xu, X PY - 2013/10/15/ UR - http://dx.doi.org/10.5194/cp-9-2319-2013 DO - doi: 10.5194/cp-9-2319-2013 ER - TY - JOUR ID - citeulike:13293743 L3 - citeulike-article-id:13293743 TI - Effects of Large Volcanic Eruptions on Global Summer Climate and East Asian Monsoon Changes during the Last Millennium: Analysis of MPI-ESM Simulations JF - J. Climate VL - 27 IS - 19 SP - 7394 EP - 7409 PB - American Meteorological Society N2 - AbstractResponses of summer [June?August (JJA)] temperature and precipitation to large volcanic eruptions are analyzed using the millennial simulations of the earth system model developed at the Max Planck Institute for Meteorology. The model was driven by up-to-date reconstructions of external forcing, including natural forcing (solar and volcanic) and anthropogenic forcing (land-cover change and greenhouse gases). Cooling anomalies after large volcanic eruptions are seen on a nearly global scale. The cooling in the Northern Hemisphere (NH) is stronger than in the Southern Hemisphere (SH), and cooling is stronger over the continents than over the oceans. The precipitation decreases in the tropical and subtropical regions in the first summer after large volcanic eruptions. The cooling, with amplitudes of up to ?0.6°C, is also seen over eastern China. East Asia is dominated by northerly wind anomalies, and the corresponding summer rainfall exhibits a coherent reduction over the entirety of eastern China. The tropospheric mean temperature anomalies indicate that there is coherent cooling over East Asia and the tropical ocean after large volcanic eruptions. The cooling over the middle-to-high latitudes of East Asia is stronger than over the tropical ocean. This temperature anomaly pattern suggests a reduced land?sea thermal contrast and favors a weaker East Asian summer monsoon (EASM) circulation. Analysis of the radiative fluxes at the top of the atmosphere (TOA) suggests that the reduction in shortwave radiation after large volcanic eruptions is nearly twice as large as the reduction in emitted longwave radiation, a net loss of radiative energy that cools the surface and lower troposphere. AbstractResponses of summer [June?August (JJA)] temperature and precipitation to large volcanic eruptions are analyzed using the millennial simulations of the earth system model developed at the Max Planck Institute for Meteorology. The model was driven by up-to-date reconstructions of external forcing, including natural forcing (solar and volcanic) and anthropogenic forcing (land-cover change and greenhouse gases). Cooling anomalies after large volcanic eruptions are seen on a nearly global scale. The cooling in the Northern Hemisphere (NH) is stronger than in the Southern Hemisphere (SH), and cooling is stronger over the continents than over the oceans. The precipitation decreases in the tropical and subtropical regions in the first summer after large volcanic eruptions. The cooling, with amplitudes of up to ?0.6°C, is also seen over eastern China. East Asia is dominated by northerly wind anomalies, and the corresponding summer rainfall exhibits a coherent reduction over the entirety of eastern China. The tropospheric mean temperature anomalies indicate that there is coherent cooling over East Asia and the tropical ocean after large volcanic eruptions. The cooling over the middle-to-high latitudes of East Asia is stronger than over the tropical ocean. This temperature anomaly pattern suggests a reduced land?sea thermal contrast and favors a weaker East Asian summer monsoon (EASM) circulation. Analysis of the radiative fluxes at the top of the atmosphere (TOA) suggests that the reduction in shortwave radiation after large volcanic eruptions is nearly twice as large as the reduction in emitted longwave radiation, a net loss of radiative energy that cools the surface and lower troposphere. KW - cmip5 KW - mpi_model KW - past1000 KW - pmip3 AU - Man, Wenmin AU - Zhou, Tianjun AU - Jungclaus, Johann PY - 2014/07/17/ UR - http://dx.doi.org/10.1175/jcli-d-13-00739.1 DO - doi: 10.1175/jcli-d-13-00739.1 ER - TY - JOUR ID - citeulike:12099158 L3 - citeulike-article-id:12099158 TI - Characteristics of the ocean simulations in the Max Planck Institute Ocean Model (MPIOM) the ocean component of the MPI-Earth system model JF - Journal of Advances in Modeling Earth Systems VL - 5 IS - 2 SP - 422 EP - 446 SN - 19422466 N2 - MPI-ESM is a new version of the global Earth system model developed at the Max Planck Institute for Meteorology. This paper describes the ocean state and circulation as well as basic aspects of variability in simulations contributing to the fifth phase of the Coupled Model Intercomparison Project (CMIP5). The performance of the ocean/sea-ice model MPIOM, coupled to a new version of the atmosphere model ECHAM6 and modules for land surface and ocean biogeochemistry, is assessed for two model versions with different grid resolution in the ocean. The low-resolution configuration has a nominal resolution of 1.5°, whereas the higher resolution version features a quasiuniform, eddy-permitting global resolution of 0.4°. The paper focuses on important oceanic features, such as surface temperature and salinity, water mass distribution, large-scale circulation, and heat and freshwater transports. In general, these integral quantities are simulated well in comparison with observational estimates, and improvements in comparison with the predecessor system are documented; for example, for tropical variability and sea ice representation. Introducing an eddy-permitting grid configuration in the ocean leads to improvements, in particular, in the representation of interior water mass properties in the Atlantic and in the representation of important ocean currents, such as the Agulhas and Equatorial current systems. In general, however, there are more similarities than differences between the two grid configurations, and several shortcomings, known from earlier versions of the coupled model, prevail. KW - cmip5 KW - mpi_model AU - Jungclaus, JH AU - Fischer, N AU - Haak, H AU - Lohmann, K AU - Marotzke, J AU - Matei, D AU - Mikolajewicz, U AU - Notz, D AU - von Storch, JS PY - 2013/06/01/ UR - http://dx.doi.org/10.1002/jame.20023 DO - doi: 10.1002/jame.20023 ER - TY - JOUR ID - citeulike:12455247 L3 - citeulike-article-id:12455247 TI - Climate and carbon cycle changes from 1850 to 2100 in MPI-ESM simulations for the Coupled Model Intercomparison Project phase 5 JF - Journal of Advances in Modeling Earth Systems VL - 5 IS - 3 SP - 572 EP - 597 SN - 19422466 N2 - The new Max-Planck-Institute Earth System Model (MPI-ESM) is used in the Coupled Model Intercomparison Project phase 5 (CMIP5) in a series of climate change experiments for either idealized CO2-only forcing or forcings based on observations and the Representative Concentration Pathway (RCP) scenarios. The paper gives an overview of the model configurations, experiments related forcings, and initialization procedures and presents results for the simulated changes in climate and carbon cycle. It is found that the climate feedback depends on the global warming and possibly the forcing history. The global warming from climatological 1850 conditions to 2080–2100 ranges from 1.5°C under the RCP2.6 scenario to 4.4°C under the RCP8.5 scenario. Over this range, the patterns of temperature and precipitation change are nearly independent of the global warming. The model shows a tendency to reduce the ocean heat uptake efficiency toward a warmer climate, and hence acceleration in warming in the later years. The precipitation sensitivity can be as high as 2.5% K−1 if the CO2 concentration is constant, or as small as 1.6% K−1, if the CO2 concentration is increasing. The oceanic uptake of anthropogenic carbon increases over time in all scenarios, being smallest in the experiment forced by RCP2.6 and largest in that for RCP8.5. The land also serves as a net carbon sink in all scenarios, predominantly in boreal regions. The strong tropical carbon sources found in the RCP2.6 and RCP8.5 experiments are almost absent in the RCP4.5 experiment, which can be explained by reforestation in the RCP4.5 scenario. KW - cmip5 KW - mpi_model KW - picontrol KW - pmip3 KW - rcp45 AU - Giorgetta, Marco AU - Jungclaus, Johann AU - Reick, Christian AU - Legutke, Stephanie AU - Bader, Jürgen AU - Böttinger, Michael AU - Brovkin, Victor AU - Crueger, Traute AU - Esch, Monika AU - Fieg, Kerstin AU - Glushak, Ksenia AU - Gayler, Veronika AU - Haak, Helmuth AU - Hollweg, Heinz-Dieter AU - Ilyina, Tatiana AU - Kinne, Stefan AU - Kornblueh, Luis AU - Matei, Daniela AU - Mauritsen, Thorsten AU - Mikolajewicz, Uwe AU - Mueller, Wolfgang AU - Notz, Dirk AU - Pithan, Felix AU - Raddatz, Thomas AU - Rast, Sebastian AU - Redler, Rene AU - Roeckner, Erich AU - Schmidt, Hauke AU - Schnur, Reiner AU - Segschneider, Joachim AU - Six, Katharina AU - Stockhause, Martina AU - Timmreck, Claudia AU - Wegner, Jörg AU - Widmann, Heinrich AU - Wieners, Karl-H AU - Claussen, Martin AU - Marotzke, Jochem AU - Stevens, Bjorn PY - 2013/07/01/ UR - http://dx.doi.org/10.1002/jame.20038 DO - doi: 10.1002/jame.20038 ER - TY - JOUR ID - citeulike:13847450 L3 - citeulike-article-id:13847450 TI - Glacial ocean overturning intensified by tidal mixing in a global circulation model JF - Geophysical Research Letters VL - 42 IS - 10 SP - 4014 EP - 4022 SN - 00948276 KW - lgm KW - osuvic_model KW - pmip3 AU - Schmittner, A AU - Green, JAM AU - Wilmes, SB PY - 2015/05/28/ UR - http://dx.doi.org/10.1002/2015gl063561 DO - doi: 10.1002/2015gl063561 ER - TY - JOUR ID - citeulike:12858842 L3 - citeulike-article-id:12858842 TI - Small influence of solar variability on climate over the past millennium JF - Nature Geoscience VL - 7 IS - 2 SP - 104 EP - 108 PB - Nature Publishing Group SN - 1752-0894 KW - cmip5 KW - hadcm_model KW - past1000 KW - pmip3 AU - Schurer, Andrew AU - Tett, Simon AU - Hegerl, Gabriele PY - 2013/12/22/ UR - http://dx.doi.org/10.1038/ngeo2040 DO - doi: 10.1038/ngeo2040 ER - TY - JOUR ID - citeulike:3855417 L3 - citeulike-article-id:3855417 TI - The impact of new physical parametrizations in the Hadley Centre climate model: HadAM3 T2 - Climate Dynamics JF - Climate Dynamics VL - 16 IS - 2-3 SP - 123 EP - 146 PB - Springer-Verlag SN - 0930-7575 N2 - Results are presented from the latest version of the Hadley Centre climate model, HadAM3 (Hadley Centre Atmospheric Model version 3). It represents a significant improvement over the previous version, HadAM2b. This is demonstrated using a series of ten year integrations with AMIP (Atmospheric Model Intercomparison Project) boundary conditions. The work covers three aspects of model performance: (1) it shows the improvements in the mean climate in changing from HadAM2b to HadAM3; (2) it demonstrates that the model now compares well with observations and (3) it isolates the impacts of new physical parametrizations. KW - cmip5 KW - hadcm_model KW - past1000 KW - pmip3 AU - Pope, VD AU - Gallani, ML AU - Rowntree, PR AU - Stratton, RA PY - 2000/02/04/ UR - http://dx.doi.org/10.1007/s003820050009 DO - doi: 10.1007/s003820050009 ER - TY - JOUR ID - citeulike:3855412 L3 - citeulike-article-id:3855412 TI - The simulation of SST, sea ice extents and ocean heat transports in a version of the Hadley Centre coupled model without flux adjustments T2 - Climate Dynamics JF - Climate Dynamics VL - 16 IS - 2-3 SP - 147 EP - 168 PB - Springer-Verlag SN - 0930-7575 N2 - Results are presented from a new version of the Hadley Centre coupled model (HadCM3) that does not require flux adjustments to prevent large climate drifts in the simulation. The model has both an improved atmosphere and ocean component. In particular, the ocean has a 1.25° × 1.25° degree horizontal resolution and leads to a considerably improved simulation of ocean heat transports compared to earlier versions with a coarser resolution ocean component. The model does not have any spin up procedure prior to coupling and the simulation has been run for over 400 years starting from observed initial conditions. The sea surface temperature (SST) and sea ice simulation are shown to be stable and realistic. The trend in global mean SST is less than 0.009 °C per century. In part, the improved simulation is a consequence of a greater compatibility of the atmosphere and ocean model heat budgets. The atmospheric model surface heat and momentum budget are evaluated by comparing with climatological ship-based estimates. Similarly the ocean model simulation of poleward heat transports is compared with direct ship-based observations for a number of sections across the globe. Despite the limitations of the observed datasets, it is shown that the coupled model is able to reproduce many aspects of the observed heat budget. KW - cmip5 KW - hadcm_model KW - past1000 KW - pmip3 AU - Gordon, C AU - Cooper, C AU - Senior, CA AU - Banks, H AU - Gregory, JM AU - Johns, TC AU - Mitchell, JFB AU - Wood, RA PY - 2000/02/04/ UR - http://dx.doi.org/10.1007/s003820050010 DO - doi: 10.1007/s003820050010 ER - TY - JOUR ID - citeulike:10176451 L3 - citeulike-article-id:10176451 TI - Climate forcing reconstructions for use in PMIP simulations of the last millennium (v1.0) JF - Geoscientific Model Development VL - 4 IS - 1 SP - 33 EP - 45 PB - Copernicus Publications N2 - Simulations of climate over the Last Millennium (850–1850 CE) have been incorporated into the third phase of the Paleoclimate Modelling Intercomparison Project (PMIP3). The drivers of climate over this period are chiefly orbital, solar, volcanic, changes in land use/land cover and some variation in greenhouse gas levels. While some of these effects can be easily defined, the reconstructions of solar, volcanic and land use-related forcing are more uncertain. We describe here the approach taken in defining the scenarios used in PMIP3, document the forcing reconstructions and discuss likely implications. KW - cmip5 KW - past1000 KW - pmip3 KW - reconstruction AU - Schmidt, GA AU - Jungclaus, JH AU - Ammann, CM AU - Bard, E AU - Braconnot, P AU - Crowley, TJ AU - Delaygue, G AU - Joos, F AU - Krivova, NA AU - Muscheler, R AU - Otto-Bliesner, BL AU - Pongratz, J AU - Shindell, DT AU - Solanki, SK AU - Steinhilber, F AU - Vieira, LEA PY - 2011/01/21/ UR - http://dx.doi.org/10.5194/gmd-4-33-2011 DO - doi: 10.5194/gmd-4-33-2011 ER - TY - JOUR ID - citeulike:12397049 L3 - citeulike-article-id:12397049 TI - Climate forcing reconstructions for use in PMIP simulations of the Last Millennium (v1.1) JF - Geoscientific Model Development VL - 5 IS - 1 SP - 185 EP - 191 PB - Copernicus Publications N2 - We update the forcings for the PMIP3 experiments for the Last Millennium to include new assessments of historical land use changes and discuss new suggestions for calibrating solar activity proxies to total solar irradiance. KW - cmip5 KW - past1000 KW - pmip3 KW - reconstruction AU - Schmidt, GA AU - Jungclaus, JH AU - Ammann, CM AU - Bard, E AU - Braconnot, P AU - Crowley, TJ AU - Delaygue, G AU - Joos, F AU - Krivova, NA AU - Muscheler, R AU - Otto-Bliesner, BL AU - Pongratz, J AU - Shindell, DT AU - Solanki, SK AU - Steinhilber, F AU - Vieira, LEA PY - 2012/01/30/ UR - http://dx.doi.org/10.5194/gmd-5-185-2012 DO - doi: 10.5194/gmd-5-185-2012 ER - TY - JOUR ID - citeulike:11809627 L3 - citeulike-article-id:11809627 TI - Can the Last Glacial Maximum constrain climate sensitivity? JF - Geophysical Research Letters VL - 39 IS - 24 SP - n/a EP - n/a SN - 00948276 KW - lgm KW - pmip2 AU - Hargreaves, JC AU - Annan, JD AU - Yoshimori, M AU - Abe-Ouchi, A PY - 2012/12/28/ UR - http://dx.doi.org/10.1029/2012gl053872 DO - doi: 10.1029/2012gl053872 ER - TY - JOUR ID - citeulike:12397031 L3 - citeulike-article-id:12397031 TI - Proxy benchmarks for intercomparison of 8.2 ka simulations JF - Climate of the Past VL - 9 IS - 1 SP - 423 EP - 432 PB - Copernicus Publications N2 - The Paleoclimate Modelling Intercomparison Project (PMIP3) now includes the 8.2 ka event as a test of model sensitivity to North Atlantic freshwater forcing. To provide benchmarks for intercomparison, we compiled and analyzed high-resolution records spanning this event. Two previously-described anomaly patterns that emerge are cooling around the North Atlantic and drier conditions in the Northern Hemisphere tropics. Newer to this compilation are more robustly-defined wetter conditions in the Southern Hemisphere tropics and regionally-limited warming in the Southern Hemisphere. Most anomalies around the globe lasted on the order of 100 to 150 yr. More quantitative reconstructions are now available and indicate cooling of ~ 1 °C and a ~ 20% decrease in precipitation in parts of Europe as well as spatial gradients in δ18O from the high to low latitudes. Unresolved questions remain about the seasonality of the climate response to freshwater forcing and the extent to which the bipolar seesaw operated in the early Holocene. KW - early_holocene KW - model_data_comparison KW - pmip3 KW - reconstruction AU - Morrill, C AU - Anderson, DM AU - Bauer, BA AU - Buckner, R AU - Gille, EP AU - Gross, WS AU - Hartman, M AU - Shah, A PY - 2013/02/19/ UR - http://dx.doi.org/10.5194/cp-9-423-2013 DO - doi: 10.5194/cp-9-423-2013 ER - TY - JOUR ID - citeulike:13847305 L3 - citeulike-article-id:13847305 TI - Megalake Chad impact on climate and vegetation during the late Pliocene and the mid-Holocene JF - Climate of the Past VL - 9 IS - 4 SP - 1417 EP - 1430 PB - Copernicus Publications N2 - Given the growing evidence for megalakes in the geological record, assessing their impact on climate and vegetation is important for the validation of palaeoclimate simulations and therefore the accuracy of model–data comparison in lacustrine environments. Megalake Chad (MLC) occurrences are documented not only for the mid-Holocene but also for the Mio-Pliocene (Schuster et al., 2009). At this time, the surface covered by water would have reached up to ~350 000 km2 (Ghienne et al., 2002; Schuster et al., 2005; Leblanc et al., 2006), making it an important evaporation source, possibly modifying climate and vegetation in the Chad Basin. We investigated the impact of such a giant continental water area in two different climatic backgrounds within the Paleoclimate Model Intercomparison Project phase 3 (PMIP3): the late Pliocene (3.3 to 3 Ma, i.e. the mid-Piacenzian warm period) and the mid-Holocene (6 kyr BP). In all simulations including MLC, precipitation is drastically reduced above the lake surface because deep convection is inhibited by overlying colder air. Meanwhile, convective activity is enhanced around MLC because of the wind increase generated by the flat surface of the megalake, transporting colder and moister air towards the eastern shore of the lake. The effect of MLC on precipitation and temperature is not sufficient to widely impact vegetation patterns. Nevertheless, tropical savanna is present in the Chad Basin in all climatic configurations, even without MLC presence, showing that the climate itself is the driver of favourable environments for sustainable hominid habitats. KW - africa KW - biome4 KW - midholocene KW - pliomip KW - pmip3 AU - Contoux, C AU - Jost, A AU - Ramstein, G AU - Sepulchre, P AU - Krinner, G AU - Schuster, M PY - 2013/07/05/ UR - http://dx.doi.org/10.5194/cp-9-1417-2013 DO - doi: 10.5194/cp-9-1417-2013 ER - TY - JOUR ID - citeulike:12783078 L3 - citeulike-article-id:12783078 TI - Northern Hemispheric cryosphere response to volcanic eruptions in the Paleoclimate Modeling Intercomparison Project 3 last millennium simulations JF - Journal of Geophysical Research: Atmospheres VL - 118 IS - 22 SP - 12,359 EP - 12,370 SN - 2169897X N2 - We analyzed last millennium simulations (circa 850–1850 Common Era) from the Paleoclimate Modeling Intercomparison Project 3 (PMIP3) project to determine whether current state-of-the-art models produce sudden changes and persistence of cold conditions after large volcanic eruptions as inferred from geological records and previous climate modeling. Snow cover over Baffin Island in the eastern Canadian Arctic shows large-scale expansion (as seen in proxy records) in two of the five models with snow cover information available, although it is not sustained beyond a decade. Sea ice expansion in the North Atlantic is seen in some PMIP3 models after large eruptions, although none of these models produce significant centennial-scale effects. Warm Baffin Island summer climates stunt snow expansion in some models completely, and model topography tends to miss the critical plateau elevations that could sustain snow on the island. Northern Hemisphere sea ice extent is lower in six of the eight models than in reconstructions over the past millennium. Annual average Northern Hemisphere mean climates have a range of 3 K across models, while Arctic summer land-only climates span more than 6 K. This has critical consequences on ice and snow formation and persistence in regions such as the Arctic where temperatures are near the freezing point and small temperature changes affect ice and snow feedback that could induce further climate changes. Thus, it is critical that models accurately represent absolute temperature. KW - arctic KW - cmip5 KW - model_data_comparison KW - past1000 KW - pmip3 AU - Berdahl, Mira AU - Robock, Alan PY - 2013/11/27/ UR - http://dx.doi.org/10.1002/2013jd019914 DO - doi: 10.1002/2013jd019914 ER - TY - JOUR ID - citeulike:13412162 L3 - citeulike-article-id:13412162 TI - The influence of atmospheric circulation on the mid-Holocene climate of Europe: a data–model comparison JF - Climate of the Past VL - 10 IS - 5 SP - 1925 EP - 1938 PB - Copernicus Publications N2 - The atmospheric circulation is a key area of uncertainty in climate model simulations of future climate change, especially in mid-latitude regions such as Europe where atmospheric dynamics have a significant role in climate variability. It has been proposed that the mid-Holocene was characterized in Europe by a stronger westerly circulation in winter comparable with a more positive AO/NAO, and a weaker westerly circulation in summer caused by anti-cyclonic blocking near Scandinavia. Model simulations indicate at best only a weakly positive AO/NAO, whilst changes in summer atmospheric circulation have not been widely investigated. Here we use a new pollen-based reconstruction of European mid-Holocene climate to investigate the role of atmospheric circulation in explaining the spatial pattern of seasonal temperature and precipitation anomalies. We find that the footprint of the anomalies is entirely consistent with those from modern analogue atmospheric circulation patterns associated with a strong westerly circulation in winter (positive AO/NAO) and a weak westerly circulation in summer associated with anti-cyclonic blocking (positive SCAND). We find little agreement between the reconstructed anomalies and those from 14 GCMs that performed mid-Holocene experiments as part of the PMIP3/CMIP5 project, which show a much greater sensitivity to top-of-the-atmosphere changes in solar insolation. Our findings are consistent with data–model comparisons on contemporary timescales that indicate that models underestimate the role of atmospheric circulation in recent climate change, whilst also highlighting the importance of atmospheric dynamics in explaining interglacial warming. KW - cmip5 KW - europa KW - midholocene KW - model_data_comparison KW - pmip3 AU - Mauri, A AU - Davis, BAS AU - Collins, PM AU - Kaplan, JO PY - 2014/10/29/ UR - http://dx.doi.org/10.5194/cp-10-1925-2014 DO - doi: 10.5194/cp-10-1925-2014 ER - TY - JOUR ID - citeulike:13847279 L3 - citeulike-article-id:13847279 TI - Present-day variations and paleodynamics of the Caspian Sea level as a standard for climate modeling data verification T2 - Russian Meteorology and Hydrology VL - 39 IS - 5 SP - 328 EP - 334 PB - Allerton Press KW - cmip5 KW - lgm KW - midholocene KW - model_data_comparison KW - past1000 KW - pmip3 KW - reconstruction AU - Kislov, AV AU - Panin, AV AU - Toropov, PA PY - 2014/// UR - http://dx.doi.org/10.3103/s1068373914050069 DO - doi: 10.3103/s1068373914050069 ER - TY - JOUR ID - citeulike:13847275 L3 - citeulike-article-id:13847275 TI - Current status and palaeostages of the Caspian Sea as a potential evaluation tool for climate model simulations JF - Quaternary International VL - 345 SP - 48 EP - 55 SN - 10406182 KW - cmip5 KW - lgm KW - midholocene KW - model_data_comparison KW - past1000 KW - pmip3 KW - reconstruction AU - Kislov, AV AU - Panin, A AU - Toropov, P PY - 2014/09// UR - http://dx.doi.org/10.1016/j.quaint.2014.05.014 DO - doi: 10.1016/j.quaint.2014.05.014 ER - TY - JOUR ID - citeulike:13847262 L3 - citeulike-article-id:13847262 TI - Rise and fall of late Pleistocene pluvial lakes in response to reduced evaporation and precipitation: Evidence from Lake Surprise, California JF - Geological Society of America Bulletin VL - 126 IS - 11-12 SP - 1387 EP - 1415 SN - 0016-7606 KW - cmip5 KW - lgm KW - model_data_comparison KW - pmip3 KW - reconstruction AU - Ibarra, Daniel AU - Egger, Anne AU - Weaver, Karrie AU - Harris, Caroline AU - Maher, Kate PY - 2014/11// UR - http://dx.doi.org/10.1130/b31014.1 DO - doi: 10.1130/b31014.1 ER - TY - JOUR ID - citeulike:13847008 L3 - citeulike-article-id:13847008 TI - Glacial cooling as inferred from marine temperature proxies TEXH86 and UK′37 JF - Earth and Planetary Science Letters VL - 409 SP - 15 EP - 22 SN - 0012821X KW - cmip5 KW - lgm KW - model_data_comparison KW - pmip3 KW - reconstruction AU - Ho, Sze AU - Laepple, Thomas PY - 2015/01// UR - http://dx.doi.org/10.1016/j.epsl.2014.10.033 DO - doi: 10.1016/j.epsl.2014.10.033 ER - TY - JOUR ID - citeulike:13535131 L3 - citeulike-article-id:13535131 TI - A comparison of model simulations of Asian mega-droughts during the past millennium with proxy reconstructions JF - Climate of the Past VL - 11 IS - 2 SP - 253 EP - 263 PB - Copernicus Publications N2 - Two PMIP3/CMIP5 climate model ensemble simulations of the past millennium have been analysed to identify the occurrence of Asian mega-droughts. The Palmer drought severity index (PDSI) is used as the key metric for the data comparison of hydro-climatological conditions. The model results are compared with the proxy data of the Monsoon Asia Drought Atlas (MADA). Our study shows that global circulation models (GCMs) are capable of capturing the majority of historically recorded Asian monsoon failures at the right time and with a comparable spatial distribution. The simulations indicate that El Niño-like events lead, in most cases, to these droughts. Both model simulations and proxy reconstructions point to fewer monsoon failures during the Little Ice Age. The results suggest an influential impact of volcanic forcing on the atmosphere–ocean interactions throughout the past millennium. During historic mega-droughts of the past millennium, the monsoon convection tends to assume a preferred regime described as a "break" event in Asian monsoon. This particular regime is coincident with a notable weakening in the Pacific trade winds and Somali Jet. KW - asia KW - cmip5 KW - enso KW - model_data_comparison KW - monsoon KW - past1000 KW - pdsi KW - pmip3 AU - Fallah, B AU - Cubasch, U PY - 2015/02/17/ UR - http://dx.doi.org/10.5194/cp-11-253-2015 DO - doi: 10.5194/cp-11-253-2015 ER - TY - JOUR ID - citeulike:13551776 L3 - citeulike-article-id:13551776 TI - Global climate simulations at 3000-year intervals for the last 21 000 years with the GENMOM coupled atmosphere–ocean model JF - Climate of the Past VL - 11 IS - 3 SP - 449 EP - 471 PB - Copernicus Publications N2 - We apply GENMOM, a coupled atmosphere–ocean climate model, to simulate eight equilibrium time slices at 3000-year intervals for the past 21 000 years forced by changes in Earth–Sun geometry, atmospheric greenhouse gases (GHGs), continental ice sheets, and sea level. Simulated global cooling during the Last Glacial Maximum (LGM) is 3.8 °C and the rate of post-glacial warming is in overall agreement with recently published temperature reconstructions. The greatest rate of warming occurs between 15 and 12 ka (2.4 °C over land, 0.7 °C over oceans, and 1.4 °C globally) in response to changes in radiative forcing from the diminished extent of the Northern Hemisphere (NH) ice sheets and increases in GHGs and NH summer insolation. The modeled LGM and 6 ka temperature and precipitation climatologies are generally consistent with proxy reconstructions, the PMIP2 and PMIP3 simulations, and other paleoclimate data–model analyses. The model does not capture the mid-Holocene "thermal maximum" and gradual cooling to preindustrial (PI) global temperature found in the data. Simulated monsoonal precipitation in North Africa peaks between 12 and 9 ka at values ~ 50% greater than those of the PI, and Indian monsoonal precipitation peaks at 12 and 9 ka at values ~ 45% greater than the PI. GENMOM captures the reconstructed LGM extent of NH and Southern Hemisphere (SH) sea ice. The simulated present-day Antarctica Circumpolar Current (ACC) is ~ 48% weaker than the observed (62 versus 119 Sv). The simulated present-day Atlantic Meridional Overturning Circulation (AMOC) of 19.3 ± 1.4 Sv on the Bermuda Rise (33° N) is comparable with observed value of 18.7 ± 4.8 Sv. AMOC at 33° N is reduced by ~ 15% during the LGM, and the largest post-glacial increase (~ 11%) occurs during the 15 ka time slice. KW - cmip5 KW - lgm KW - midholocene KW - model_data_comparison KW - pmip2 KW - pmip3 AU - Alder, JR AU - Hostetler, SW PY - 2015/03/17/ UR - http://dx.doi.org/10.5194/cp-11-449-2015 DO - doi: 10.5194/cp-11-449-2015 ER - TY - JOUR ID - citeulike:13688243 L3 - citeulike-article-id:13688243 TI - Interhemispheric dynamics of the African rainbelt during the late Quaternary JF - Quaternary Science Reviews VL - 124 SP - 48 EP - 67 SN - 02773791 N2 - We use model simulations for the last 120 kyr to explore African rainbelt variations. The simulations were compared with existing empirical palaeohydrological records. We find validity in several hypotheses for mechanisms of hydroclimate variation. These mechanisms occur concurrently, with different regional emphases. The mechanisms forcing rainbelt variations vary temporally as well as spatially. The spatial pattern of precipitation variability in tropical and subtropical Africa over the late Quaternary has long been debated. Prevailing hypotheses variously infer (1) insolation-controlled asymmetry of wet phases between hemispheres, (2) symmetric contraction and expansion of the tropical rainbelt, and (3) independent control on moisture available in Southern Africa via sea surface temperatures in the Indian Ocean. In this study we use climate-model simulations covering the last glacial cycle (120 kyr) with HadCM3 and the multi-model ensembles from PMIP3 (the Palaeoclimate Model Intercomparison Project) to investigate the long-term behaviour of the African rainbelt, and test these simulations against existing empirical palaeohydrological records. Through regional model-data comparisons we find evidence for the validity of several hypotheses, with various proposed processes occurring concurrently but with different regional emphasis (e.g. asymmetric shifts at the seasonal extremes and symmetric expansions/contractions towards West equatorial regions). Crucially, variations in rainfall are associated with multiple forcing mechanisms that vary in their dominance both spatially and temporally over the glacial cycle; an important consideration when interpreting and extrapolating from often relatively short palaeoenvironmental records. KW - africa KW - cmip5 KW - itcz KW - last_glacial_cycle KW - lgm KW - midholocene KW - model_data_comparison KW - pmip3 AU - Singarayer, Joy AU - Burrough, Sallie PY - 2015/09// UR - http://dx.doi.org/10.1016/j.quascirev.2015.06.021 DO - doi: 10.1016/j.quascirev.2015.06.021 ER - TY - JOUR ID - citeulike:12515526 L3 - citeulike-article-id:12515526 TI - Can an Earth System Model simulate better climate change at mid-Holocene than an AOGCM? A comparison study of MIROC-ESM and MIROC3 JF - Climate of the Past VL - 9 IS - 4 SP - 1519 EP - 1542 PB - Copernicus Publications N2 - The importance of evaluating models through paleoclimate simulations is becoming more recognized in efforts to improve climate projection. To evaluate an integrated Earth System Model, MIROC-ESM, we performed simulations in time-slice experiments for the mid-Holocene (6000 yr before present, 6 ka) and preindustrial (1850 AD, 0 ka) periods under the protocol of the Coupled Model Intercomparison Project 5/Paleoclimate Modelling Intercomparison Project 3. We first give an overview of the simulated global climates by comparing with simulations using a previous version of the MIROC model (MIROC3), which is an atmosphere–ocean coupled general circulation model. We then comprehensively discuss various aspects of climate change with 6 ka forcing and how the differences in the models can affect the results. We also discuss the representation of the precipitation enhancement at 6 ka over northern Africa. The precipitation enhancement at 6 ka over northern Africa according to MIROC-ESM does not differ greatly from that obtained with MIROC3, which means that newly developed components such as dynamic vegetation and improvements in the atmospheric processes do not have significant impacts on the representation of the 6 ka monsoon change suggested by proxy records. Although there is no drastic difference between the African monsoon representations of the two models, there are small but significant differences in the precipitation enhancement over the Sahara in early summer, which can be related to the representation of the sea surface temperature rather than the vegetation coupling in MIROC-ESM. Because the oceanic parts of the two models are identical, the difference in the sea surface temperature change is ultimately attributed to the difference in the atmospheric and/or land modules, and possibly the difference in the representation of low-level clouds. KW - cmip5 KW - midholocene KW - miroc_model KW - picontrol KW - pmip3 AU - Ohgaito, R AU - Sueyoshi, T AU - Abe-Ouchi, A AU - Hajima, T AU - Watanabe, S AU - Kim, HJ AU - Yamamoto, A AU - Kawamiya, M PY - 2013/07/19/ UR - http://dx.doi.org/10.5194/cp-9-1519-2013 DO - doi: 10.5194/cp-9-1519-2013 ER - TY - JOUR ID - citeulike:13476153 L3 - citeulike-article-id:13476153 TI - Solar forcing of Earth's surface temperature in PMIP3 simulations of the last millennium JF - Atmospheric Science Letters VL - 16 IS - 3 SP - 285 EP - 290 PB - John Wiley & Sons, Ltd SN - 1530261X N2 - This study quantitatively diagnose the linkage between Total Solar Irradiance (TSI) and Earth's near-surface air temperature (TAS) of past 1000-year as simulated by Paleoclimate Modeling Intercomparison Project 3 (PMIP3) models. The results demonstrate that there is causal feedback of TAS from TSI variations, especially in the tropical and subtropical regions. The consistency between models in simulating solar signal in TAS responses is significant in these regions with more than 70% selected models showing agreement. There is no agreement between models in simulating TSI-TAS relationship in mid and high latitude regions. KW - cmip5 KW - past1000 KW - pmip3 AU - Le, Thanh PY - 2015/07/01/ UR - http://dx.doi.org/10.1002/asl2.555 DO - doi: 10.1002/asl2.555 ER - TY - JOUR ID - citeulike:13845086 L3 - citeulike-article-id:13845086 TI - Last Glacial Maximum climate over Korean Peninsula in PMIP3 simulations JF - Quaternary International VL - 384 SP - 52 EP - 81 SN - 10406182 KW - cmip5 KW - lgm KW - pmip3 AU - Kim, Seong-Joong AU - Kim, Ji-Won AU - Kim, Baek-Min PY - 2015/10// UR - http://dx.doi.org/10.1016/j.quaint.2015.02.062 DO - doi: 10.1016/j.quaint.2015.02.062 ER - TY - JOUR ID - citeulike:13844994 L3 - citeulike-article-id:13844994 TI - The de-correlation of westerly winds and westerly-wind stress over the Southern Ocean during the Last Glacial Maximum T2 - Climate Dynamics VL - 45 IS - 11-12 SP - 3157 EP - 3168 PB - Springer Berlin Heidelberg KW - antarctica KW - cmip5 KW - lgm KW - pmip3 KW - wind AU - Liu, Wei AU - Lu, Jian AU - Leung AU - Xie, Shang-Ping AU - Liu, Zhengyu AU - Zhu, Jiang PY - 2015/// UR - http://dx.doi.org/10.1007/s00382-015-2530-4 DO - doi: 10.1007/s00382-015-2530-4 ER - TY - JOUR ID - citeulike:13842569 L3 - citeulike-article-id:13842569 TI - What drives LGM precipitation over the western Mediterranean? A study focused on the Iberian Peninsula and northern Morocco T2 - Climate Dynamics SP - 1 EP - 21 PB - Springer Berlin Heidelberg KW - cmip5 KW - lgm KW - mediterranean KW - pmip3 AU - Beghin, P AU - Charbit, S AU - Kageyama, M AU - Combourieu-Nebout, N AU - Hatté, C AU - Dumas, C AU - Peterschmitt, JY PY - 2015/// UR - http://dx.doi.org/10.1007/s00382-015-2720-0 DO - doi: 10.1007/s00382-015-2720-0 ER - TY - JOUR ID - citeulike:13841933 L3 - citeulike-article-id:13841933 TI - Persistent influence of ice sheet melting on high northern latitude climate during the early Last Interglacial JF - Climate of the Past VL - 8 IS - 2 SP - 483 EP - 507 PB - Copernicus Publications N2 - Although the Last Interglacial (LIG) is often considered as a possible analogue for future climate in high latitudes, its precise climate evolution and associated causes remain uncertain. Here we compile high-resolution marine sediment records from the North Atlantic, Labrador Sea, Norwegian Sea and the Southern Ocean. We document a delay in the establishment of peak interglacial conditions in the North Atlantic, Labrador and Norwegian Seas as compared to the Southern Ocean. In particular, we observe a persistent iceberg melting at high northern latitudes at the beginning of the LIG. It is associated with (1) colder and fresher surface-water conditions in the North Atlantic, Labrador and Norwegian Seas, and (2) a weaker ventilation of North Atlantic deep waters during the early LIG (129–125 ka) compared to the late LIG. Results from an ocean-atmosphere coupled model with insolation as a sole forcing for three key periods of the LIG show warmer North Atlantic surface waters and stronger Atlantic overturning during the early LIG (126 ka) than the late LIG (122 ka). Hence, insolation variations alone do not explain the delay in peak interglacial conditions observed at high northern latitudes. Additionally, we consider an idealized meltwater scenario at 126 ka where the freshwater input is interactively computed in response to the high boreal summer insolation. The model simulates colder, fresher North Atlantic surface waters and weaker Atlantic overturning during the early LIG (126 ka) compared to the late LIG (122 ka). This result suggests that both insolation and ice sheet melting have to be considered to reproduce the climatic pattern that we identify during the early LIG. Our model-data comparison also reveals a number of limitations and reinforces the need for further detailed investigations using coupled climate-ice sheet models and transient simulations. KW - ipsl_model KW - last_interglacial KW - pmip2 KW - reconstruction AU - Govin, A AU - Braconnot, P AU - Capron, E AU - Cortijo, E AU - Duplessy, JC AU - Jansen, E AU - Labeyrie, L AU - Landais, A AU - Marti, O AU - Michel, E AU - Mosquet, E AU - Risebrobakken, B AU - Swingedouw, D AU - Waelbroeck, C PY - 2012/03/14/ UR - http://dx.doi.org/10.5194/cp-8-483-2012 DO - doi: 10.5194/cp-8-483-2012 ER - TY - JOUR ID - citeulike:8973051 L3 - citeulike-article-id:8973051 TI - Impact of Earth’s orbit and freshwater fluxes on Holocene climate mean seasonal cycle and ENSO characteristics T2 - Climate Dynamics JF - Climate Dynamics VL - 38 IS - 5-6 SP - 1081 EP - 1092 PB - Springer-Verlag SN - 0930-7575 N2 - We use a state-of-the-art 3-dimensional coupled model to investigate the relative impact of long term variations in the Holocene insolation forcing and of a freshwater release in the North Atlantic. We show that insolation has a greater effect on seasonality and La Niña events and is the major driver of sea surface temperature changes. In contrast, the variations in precipitation reflect changes in El Niño events. The impact of ice-sheet melting may have offset the impact of insolation on El Niño Southern Oscillation variability at the beginning of the Holocene. These simulations provide a coherent framework to refine the interpretation of proxy data and show that changes in seasonality may bias the projection of relationships established between proxy indicators and climate variations in the east Pacific from present day records. KW - early_holocene KW - enso KW - ipsl_model KW - midholocene KW - pmip2 AU - Braconnot, P AU - Luan, Y AU - Brewer, Simon AU - Zheng, W PY - 2012/03/03/ UR - http://dx.doi.org/10.1007/s00382-011-1029-x DO - doi: 10.1007/s00382-011-1029-x ER - TY - JOUR ID - citeulike:13841911 L3 - citeulike-article-id:13841911 TI - A reassessment of lake and wetland feedbacks on the North African Holocene climate JF - Geophysical Research Letters VL - 39 IS - 7 SP - n/a EP - n/a SN - 00948276 KW - early_holocene KW - ipsl_model KW - midholocene KW - pmip2 AU - Krinner, G AU - Lézine, AM AU - Braconnot, P AU - Sepulchre, P AU - Ramstein, G AU - Grenier, C AU - Gouttevin, I PY - 2012/04// UR - http://dx.doi.org/10.1029/2012gl050992 DO - doi: 10.1029/2012gl050992 ER - TY - JOUR ID - citeulike:13841907 L3 - citeulike-article-id:13841907 TI - Early and mid-Holocene climate in the tropical Pacific: seasonal cycle and interannual variability induced by insolation changes JF - Climate of the Past VL - 8 IS - 3 SP - 1093 EP - 1108 PB - Copernicus Publications N2 - Using a coupled atmosphere-ocean model we analyze the responses of the mean climate and interannual variations in the tropical Pacific to the changes in insolation during the early and mid-Holocene, with experiments in which only the variations of Earth's orbital configuration are considered. We first discuss common features of the Early and mid-Holocene climates compared to the pre-industrial conditions. In particular, an equatorial annual mean cooling that has a "U" shape across the tropical Pacific is simulated, whereas the ocean heat content is enhanced in the western tropical Pacific and decreased in the east. Similarly, the seasonality is enhanced in the west and reduced in the east. We show that the seasonality of the insolation forcing, the cloud radiative forcing and ocean dynamics all contribute to increasing these east–west contrasts. ENSO variability is reduced in the early Holocene and increases towards present-day conditions. Obliquity alone does not affect ENSO characteristics in the model. The reduction of ENSO magnitude results from the relationship between changes in seasonality, which involves wave propagation along the thermocline, and the timing of the development of ENSO anomalies. All these effects are larger in the Early Holocene compared to the mid-Holocene. Despite a one-month difference in the insolation forcing and corresponding response of SST, winds and thermocline depth between these two periods, the timing and changes in the east–west temperature and heat content gradients are similar. We suggest that it explains why the timing of development of ENSO is quite similar between these two climates and does not reflect the differences in the seasonal timing. KW - early_holocene KW - ipsl_model KW - midholocene KW - pmip2 KW - tropics AU - Luan, Y AU - Braconnot, P AU - Yu, Y AU - Zheng, W AU - Marti, O PY - 2012/06/29/ UR - http://dx.doi.org/10.5194/cp-8-1093-2012 DO - doi: 10.5194/cp-8-1093-2012 ER - TY - JOUR ID - citeulike:12792535 L3 - citeulike-article-id:12792535 TI - Relative impacts of insolation changes, meltwater fluxes and ice sheets on African and Asian monsoons during the Holocene T2 - Climate Dynamics VL - 41 IS - 9-10 SP - 2267 EP - 2286 PB - Springer Berlin Heidelberg N2 - In order to better understand the evolution of the Afro-Asian monsoon in the early Holocene, we investigate the impact on boreal summer monsoon characteristics of (1) a freshwater flux in the North Atlantic from the surrounding melting ice sheets and (2) a remnant ice sheet over North America and Europe. Sensitivity experiments run with the IPSL_CM4 model show that both the meltwater flux and the remnant ice sheets induce a cooling of similar amplitude of the North Atlantic leading to a southward shift of the Inter-Tropical Convergence Zone over the tropical Atlantic and to a reduction of the African monsoon. The two perturbations have different impacts in the Asian sector. The meltwater flux results in a weakening of the Indian monsoon and no change in the East Asian monsoon, whereas the remnant ice sheets induce a strengthening of the Indian monsoon and a strong weakening of the East Asian monsoon. Despite the similar coolings in the Atlantic Ocean, the ocean heat transport is reduced only in the meltwater flux experiment, which induces slight differences between the two experiments in the role of the surface latent heat flux in the tropical energetics. In the meltwater experiment, the southward shift of the subtropical jet acts to cool the upper atmosphere over the Tibetan Plateau and hence to weaken the Indian monsoon. In the ice sheet experiment this effect is overwhelmed by the changes in extratropical stationary waves induced by the ice sheets, which are associated with a larger cooling over the Eurasian continent than in the meltwater experiment. However these sensitivity experiments suggest that insolation is the dominant factor explaining the relative changes of the African, Indian and East Asian monsoons from the early to the mid-Holocene. KW - early_holocene KW - ipsl_model KW - midholocene KW - monsoon KW - pmip2 AU - Marzin, Charline AU - Braconnot, Pascale AU - Kageyama, Masa PY - 2013/// UR - http://dx.doi.org/10.1007/s00382-013-1948-9 DO - doi: 10.1007/s00382-013-1948-9 ER - TY - JOUR ID - citeulike:13018431 L3 - citeulike-article-id:13018431 TI - Glacial fluctuations of the Indian monsoon and their relationship with North Atlantic climate: new data and modelling experiments JF - Climate of the Past VL - 9 IS - 5 SP - 2135 EP - 2151 PB - Copernicus Publications N2 - Several paleoclimate records such as from Chinese loess, speleothems or upwelling indicators in marine sediments present large variations of the Asian monsoon system during the last glaciation. Here, we present a new record from the northern Andaman Sea (core MD77-176) which shows the variations of the hydrological cycle of the Bay of Bengal. The high-resolution record of surface water δ18O dominantly reflects salinity changes and displays large millennial-scale oscillations over the period 40 000 to 11 000 yr BP. Their timing and sequence suggests that events of high (resp. low) salinity in the Bay of Bengal, i.e. weak (resp. strong) Indian monsoon, correspond to cold (resp. warm) events in the North Atlantic and Arctic, as documented by the Greenland ice core record. We use the IPSL_CM4 Atmosphere-Ocean coupled General Circulation Model to study the processes that could explain the teleconnection between the Indian monsoon and the North Atlantic climate. We first analyse a numerical experiment in which such a rapid event in the North Atlantic is obtained under glacial conditions by increasing the freshwater flux in the North Atlantic, which results in a reduction of the intensity of the Atlantic meridional overturning circulation. This freshwater hosing results in a weakening of the Indian monsoon rainfall and circulation. The changes in the continental runoff and local hydrological cycle are responsible for an increase in salinity in the Bay of Bengal. This therefore compares favourably with the new sea water δ18O record presented here and the hypothesis of synchronous cold North Atlantic and weak Indian monsoon events. Additional sensitivity experiments are produced with the LMDZ atmospheric model to analyse the teleconnection mechanisms between the North Atlantic and the Indian monsoon. The changes over the tropical Atlantic are shown to be essential in triggering perturbations of the subtropical jet over Africa and Eurasia, that in turn affect the intensity of the Indian monsoon. These relationships are also found to be valid in additional coupled model simulations in which the Atlantic meridional overturning circulation (AMOC) is forced to resume. KW - ipsl_model KW - lgm KW - model_data_comparison KW - monsoon KW - pmip2 KW - reconstruction AU - Marzin, C AU - Kallel, N AU - Kageyama, M AU - Duplessy, JC AU - Braconnot, P PY - 2013/09/12/ UR - http://dx.doi.org/10.5194/cp-9-2135-2013 DO - doi: 10.5194/cp-9-2135-2013 ER - TY - JOUR ID - citeulike:13318416 L3 - citeulike-article-id:13318416 TI - Holocene history of ENSO variance and asymmetry in the eastern tropical Pacific JF - Science VL - 345 IS - 6200 SP - 1045 EP - 1048 PB - American Association for the Advancement of Science SN - 1095-9203 N2 - El Niño has changed quite a bit over the past 10,000 years. During some periods it was less variable than now, and during others it shifted from its current locale toward the central Pacific. Carré et al. analyzed the shells of mollusks from Peru to construct a record of the El Niño–Southern Oscillation (ENSO) in the eastern Pacific over the Holocene period. They compared this record with other records from the rest of the Pacific to reveal how much the strength and frequency of El Niños changed and how their positions varied. KW - early_holocene KW - enso KW - midholocene KW - pmip3 KW - reconstruction KW - tropics AU - Carré, Matthieu AU - Sachs, Julian AU - Purca, Sara AU - Schauer, Andrew AU - Braconnot, Pascale AU - Falcón, Rommel AU - Julien, Michèle AU - Lavallée, Danièle PY - 2014/08/29/ UR - http://dx.doi.org/10.1126/science.1252220 DO - doi: 10.1126/science.1252220 ER - TY - JOUR ID - citeulike:13841889 L3 - citeulike-article-id:13841889 TI - Tropical Pacific mean state and ENSO changes: sensitivity to freshwater flux and remnant ice sheets at 9.5 ka BP T2 - Climate Dynamics VL - 44 IS - 3-4 SP - 661 EP - 678 PB - Springer Berlin Heidelberg KW - early_holocene KW - enso KW - pmip3 KW - tropics AU - Luan, Yihua AU - Braconnot, Pascale AU - Yu, Yongqiang AU - Zheng, Weipeng PY - 2015/// UR - http://dx.doi.org/10.1007/s00382-015-2467-7 DO - doi: 10.1007/s00382-015-2467-7 ER - TY - JOUR ID - citeulike:10502172 L3 - citeulike-article-id:10502172 TI - Evaluation of climate models using palaeoclimatic data JF - Nature Climate Change VL - 2 IS - 6 SP - 417 EP - 424 PB - Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. SN - 1758-678X KW - lgm KW - midholocene KW - model_data_comparison KW - pmip2 AU - Braconnot, Pascale AU - Harrison, Sandy AU - Kageyama, Masa AU - Bartlein, Patrick AU - Masson-Delmotte, Valerie AU - Abe-Ouchi, Ayako AU - Otto-Bliesner, Bette AU - Zhao, Yan PY - 2012/03/25/ UR - http://dx.doi.org/10.1038/nclimate1456 DO - doi: 10.1038/nclimate1456 ER - TY - JOUR ID - citeulike:13841886 L3 - citeulike-article-id:13841886 TI - A multi-model assessment of last interglacial temperatures JF - Climate of the Past VL - 9 IS - 2 SP - 699 EP - 717 PB - Copernicus Publications N2 - The last interglaciation (~130 to 116 ka) is a time period with a strong astronomically induced seasonal forcing of insolation compared to the present. Proxy records indicate a significantly different climate to that of the modern, in particular Arctic summer warming and higher eustatic sea level. Because the forcings are relatively well constrained, it provides an opportunity to test numerical models which are used for future climate prediction. In this paper we compile a set of climate model simulations of the early last interglaciation (130 to 125 ka), encompassing a range of model complexities. We compare the simulations to each other and to a recently published compilation of last interglacial temperature estimates. We show that the annual mean response of the models is rather small, with no clear signal in many regions. However, the seasonal response is more robust, and there is significant agreement amongst models as to the regions of warming vs cooling. However, the quantitative agreement of the model simulations with data is poor, with the models in general underestimating the magnitude of response seen in the proxies. Taking possible seasonal biases in the proxies into account improves the agreement, but only marginally. However, a lack of uncertainty estimates in the data does not allow us to draw firm conclusions. Instead, this paper points to several ways in which both modelling and data could be improved, to allow a more robust model–data comparison. KW - last_interglacial KW - model_data_comparison KW - pmip3 AU - Lunt, DJ AU - Abe-Ouchi, A AU - Bakker, P AU - Berger, A AU - Braconnot, P AU - Charbit, S AU - Fischer, N AU - Herold, N AU - Jungclaus, JH AU - Khon, VC AU - Krebs-Kanzow, U AU - Langebroek, PM AU - Lohmann, G AU - Nisancioglu, KH AU - Otto-Bliesner, BL AU - Park, W AU - Pfeiffer, M AU - Phipps, SJ AU - Prange, M AU - Rachmayani, R AU - Renssen, H AU - Rosenbloom, N AU - Schneider, B AU - Stone, EJ AU - Takahashi, K AU - Wei, W AU - Yin, Q AU - Zhang, ZS PY - 2013/03/14/ UR - http://dx.doi.org/10.5194/cp-9-699-2013 DO - doi: 10.5194/cp-9-699-2013 ER - TY - JOUR ID - citeulike:12075879 L3 - citeulike-article-id:12075879 TI - Characterization of Model Spread in PMIP2 Mid-Holocene Simulations of the African Monsoon T2 - Journal of Climate JF - J. Climate VL - 26 IS - 4 SP - 1192 EP - 1210 PB - American Meteorological Society N2 - AbstractSimulations of the West African monsoon (WAM) for the present-day climate (0 ka) and the mid-Holocene (6 ka) using the coupled models from the Paleoclimate Modelling Intercomparison Project phase 2 (PMIP2) are assessed in this study. The authors first compare the ensemble simulations with modern observations and proxy estimates of past precipitation, showing that the PMIP2 model median captures the basic features of the WAM for 0 ka and the changes at 6 ka, despite systematic biases in the preindustrial (PI) simulations and underestimates of the northward extent and intensity of precipitation changes.The model spread is then discussed based on a classification of the monsoonal convective regimes for a subset of seven coupled models. Two major categories of model are defined based on their differences in simulating deep and moderate convective regimes in the PI simulations. Changes in precipitation at 6 ka are dominated by changes in the large-scale dynamics for most of the PMIP2 models and are characterized by a shift in the monsoonal circulation toward deeper convective regimes. Consequently, changes in the total precipitation at 6 ka depend on the changes in convective regimes and the characteristics of these regimes in the PI simulations. The results indicate that systematic model biases in simulating the radiation and heat fluxes could explain the damping of the meridional temperature gradient over West Africa and thereby the underestimation of precipitation in the Sahel?Sahara region. KW - midholocene KW - model_data_comparison KW - monsoon KW - pmip2 AU - Zheng, Weipeng AU - Braconnot, Pascale PY - 2012/08/20/ UR - http://dx.doi.org/10.1175/jcli-d-12-00071.1 DO - doi: 10.1175/jcli-d-12-00071.1 ER - TY - JOUR ID - citeulike:13841876 L3 - citeulike-article-id:13841876 TI - Changes in the ENSO/SPCZ relationship from past to future climates JF - Earth and Planetary Science Letters VL - 412 SP - 18 EP - 24 SN - 0012821X KW - abrupt4xco2 KW - cmip5 KW - enso KW - lgm KW - midholocene KW - model_data_comparison KW - picontrol KW - pmip3 KW - spcz AU - Saint-Lu, Marion AU - Braconnot, Pascale AU - Leloup, Julie AU - Lengaigne, Matthieu AU - Marti, Olivier PY - 2015/02// UR - http://dx.doi.org/10.1016/j.epsl.2014.12.033 DO - doi: 10.1016/j.epsl.2014.12.033 ER - TY - JOUR ID - citeulike:13682940 L3 - citeulike-article-id:13682940 TI - Evaluation of CMIP5 palaeo-simulations to improve climate projections JF - Nature Climate Change VL - 5 IS - 8 SP - 735 EP - 743 PB - Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. SN - 1758-678X KW - cmip5 KW - lgm KW - midholocene KW - past1000 KW - pmip3 AU - Harrison, SP AU - Bartlein, PJ AU - Izumi, K AU - Li, G AU - Annan, J AU - Hargreaves, J AU - Braconnot, P AU - Kageyama, M PY - 2015/07/24/ UR - http://dx.doi.org/10.1038/nclimate2649 DO - doi: 10.1038/nclimate2649 ER - TY - JOUR ID - citeulike:13841836 L3 - citeulike-article-id:13841836 TI - Shortwave forcing and feedbacks in Last Glacial Maximum and Mid-Holocene PMIP3 simulations JF - Phil. Trans. R. Soc. A VL - 373 IS - 2054 SP - 20140424 PB - The Royal Society SN - 1471-2962 KW - cmip5 KW - lgm KW - midholocene KW - pmip3 AU - Braconnot, Pascale AU - Kageyama, Masa PY - 2015/11/13/ UR - http://dx.doi.org/10.1098/rsta.2014.0424 DO - doi: 10.1098/rsta.2014.0424 ER - TY - JOUR ID - citeulike:13830190 L3 - citeulike-article-id:13830190 TI - Ice-sheet configuration in the CMIP5/PMIP3 Last Glacial Maximum experiments JF - Geoscientific Model Development VL - 8 IS - 11 SP - 3621 EP - 3637 PB - Copernicus Publications N2 - We describe the creation of a data set describing changes related to the presence of ice sheets, including ice-sheet extent and height, ice-shelf extent, and the distribution and elevation of ice-free land at the Last Glacial Maximum (LGM), which were used in LGM experiments conducted as part of the fifth phase of the Coupled Modelling Intercomparison Project (CMIP5) and the third phase of the Palaeoclimate Modelling Intercomparison Project (PMIP3). The CMIP5/PMIP3 data sets were created from reconstructions made by three different groups, which were all obtained using a model-inversion approach but differ in the assumptions used in the modelling and in the type of data used as constraints. The ice-sheet extent in the Northern Hemisphere (NH) does not vary substantially between the three individual data sources. The difference in the topography of the NH ice sheets is also moderate, and smaller than the differences between these reconstructions (and the resultant composite reconstruction) and ice-sheet reconstructions used in previous generations of PMIP. Only two of the individual reconstructions provide information for Antarctica. The discrepancy between these two reconstructions is larger than the difference for the NH ice sheets, although still less than the difference between the composite reconstruction and previous PMIP ice-sheet reconstructions. Although largely confined to the ice-covered regions, differences between the climate response to the individual LGM reconstructions extend over the North Atlantic Ocean and Northern Hemisphere continents, partly through atmospheric stationary waves. Differences between the climate response to the CMIP5/PMIP3 composite and any individual ice-sheet reconstruction are smaller than those between the CMIP5/PMIP3 composite and the ice sheet used in the last phase of PMIP (PMIP2). KW - antarctica KW - cmip5 KW - lgm KW - pmip3 KW - reconstruction AU - Abe-Ouchi, A AU - Saito, F AU - Kageyama, M AU - Braconnot, P AU - Harrison, SP AU - Lambeck, K AU - Otto-Bliesner, BL AU - Peltier, WR AU - Tarasov, L AU - Peterschmitt, JY AU - Takahashi, K PY - 2015/11/06/ UR - http://dx.doi.org/10.5194/gmd-8-3621-2015 DO - doi: 10.5194/gmd-8-3621-2015 ER - TY - JOUR ID - citeulike:13841677 L3 - citeulike-article-id:13841677 TI - Comparing past accumulation rate reconstructions in {E}ast {A}ntarctic ice cores using {1}0Be, water isotopes and CMIP5-PMIP3 models JF - Climate of the Past VL - 11 IS - 3 SP - 355 EP - 367 PB - Copernicus Publications N2 - Ice cores are exceptional archives which allow us to reconstruct a wealth of climatic parameters as well as past atmospheric composition over the last 800 kyr in Antarctica. Inferring the variations in past accumulation rate in polar regions is essential both for documenting past climate and for ice core chronology. On the East Antarctic Plateau, the accumulation rate is so small that annual layers cannot be identified and accumulation rate is mainly deduced from the water isotopic composition assuming constant temporal relationships between temperature, water isotopic composition and accumulation rate. Such an assumption leads to large uncertainties on the reconstructed past accumulation rate. Here, we use high-resolution beryllium-10 (10Be) as an alternative tool for inferring past accumulation rate for the EPICA Dome C ice core, in East Antarctica. We present a high-resolution 10Be record covering a full climatic cycle over the period 269 to 355 ka from Marine Isotope Stage (MIS) 9 to 10, including a period warmer than pre-industrial (MIS 9.3 optimum). After correcting 10Be for the estimated effect of the palaeomagnetic field, we deduce that the 10Be reconstruction is in reasonably good agreement with EDC3 values for the full cycle except for the period warmer than present. For the latter, the accumulation is up to 13% larger (4.46 cm ie yr−1 instead of 3.95). This result is in agreement with the studies suggesting an underestimation of the deuterium-based accumulation for the optimum of the Holocene (Parrenin et al. 2007a). Using the relationship between accumulation rate and surface temperature from the saturation vapour relationship, the 10Be-based accumulation rate reconstruction suggests that the temperature increase between the MIS 9.3 optimum and present day may be 2.4 K warmer than estimated by the water isotopes reconstruction. We compare these reconstructions to the available model results from CMIP5-PMIP3 for a glacial and an interglacial state, i.e. for the Last Glacial Maximum and pre-industrial climates. While 3 out of 7 models show relatively good agreement with the reconstructions of the accumulation–temperature relationships based on 10Be and water isotopes, the other models either underestimate or overestimate it, resulting in a range of model results much larger than the range of the reconstructions. Indeed, the models can encounter some difficulties in simulating precipitation changes linked with temperature or water isotope content on the East Antarctic Plateau during glacial–interglacial transition and need to be improved in the future. KW - antarctica KW - cmip5 KW - lgm KW - model_data_comparison KW - picontrol KW - pmip3 AU - Cauquoin, A AU - Landais, A AU - Raisbeck, GM AU - Jouzel, J AU - Bazin, L AU - Kageyama, M AU - Peterschmitt, JY AU - Werner, M AU - Bard, E AU - ASTER Team PY - 2015/03/05/ UR - http://dx.doi.org/10.5194/cp-11-355-2015 DO - doi: 10.5194/cp-11-355-2015 ER - TY - JOUR ID - citeulike:13841239 L3 - citeulike-article-id:13841239 TI - Climate-driven expansion of blanket bogs in {B}ritain during the {H}olocene JF - Climate of the Past Discussions VL - 11 IS - 5 SP - 4811 EP - 4832 PB - Copernicus Publications N2 - Blanket bog occupies approximately 6 % of the area of the UK today. The Holocene expansion of this hyperoceanic biome has previously been explained as a consequence of Neolithic forest clearance. However, the present distribution of blanket bog in Great Britain can be predicted accurately with a simple model (PeatStash) based on summer temperature and moisture index thresholds, and the same model correctly predicts the highly disjunct distribution of blanket bog worldwide. This finding suggests that climate, rather than land-use history, controls blanket-bog distribution in the UK and everywhere else.

We set out to test this hypothesis for blanket bogs in the UK using bioclimate envelope modelling compared with a database of peat initiation age estimates. We used both pollen-based reconstructions and climate model simulations of climate changes between the mid-Holocene (6000 yr BP, 6 ka) and modern climate to drive PeatStash and predict areas of blanket bog. We compiled data on the timing of blanket-bog initiation, based on 228 age determinations at sites where peat directly overlies mineral soil. The model predicts large areas of northern Britain would have had blanket bog by 6000 yr BP, and the area suitable for peat growth extended to the south after this time. A similar pattern is shown by the basal peat ages and new blanket bog appeared over a larger area during the late Holocene, the greatest expansion being in Ireland, Wales and southwest England, as the model predicts. The expansion was driven by a summer cooling of about 2 °C, shown by both pollen-based reconstructions and climate models. The data show early Holocene (pre-Neolithic) blanket-bog initiation at over half of the sites in the core areas of Scotland, and northern England.

The temporal patterns and concurrence of the bioclimate model predictions and initiation data suggest that climate change provides a parsimonious explanation for the early Holocene distribution and later expansion of blanket bogs in the UK, and it is not necessary to invoke anthropogenic activity as a driver of this major landscape change. KW - midholocene KW - model_data_comparison KW - pmip3 AU - Gallego-Sala, AV AU - Charman, DJ AU - Harrison, SP AU - Li, G AU - Prentice, IC PY - 2015/10/12/ UR - http://dx.doi.org/10.5194/cpd-11-4811-2015 DO - doi: 10.5194/cpd-11-4811-2015 ER - TY - JOUR ID - citeulike:13813260 L3 - citeulike-article-id:13813260 TI - Tropical cyclone genesis potential across palaeoclimates JF - Climate of the Past VL - 11 IS - 10 SP - 1433 EP - 1451 PB - Copernicus Publications N2 - The favourability of the mid-Pliocene, Last Glacial Maximum (LGM) and mid-Holocene for tropical cyclone formation is investigated in five climate models. This is measured by a genesis potential index, derived from large-scale atmospheric properties known to be related to storm formation. The mid-Pliocene and Last Glacial Maximum (LGM) were periods where carbon dioxide levels were higher and lower than preindustrial levels respectively, while the mid-Holocene differed primarily in its orbital configuration. The cumulative global genesis potential is found to be fairly invariant across the palaeoclimates in the multi-model mean. Despite this all ensemble members agree on coherent responses in the spatial patterns of genesis potential change.

During the mid-Pliocene and LGM, changes in carbon dioxide led to sea surface temperature changes throughout the tropics, yet the potential intensity (a measure associated with maximum tropical cyclone strength) is calculated to be relatively insensitive to these changes. Changes in tropical cyclone genesis potential during the mid-Holocene are found to be asymmetric about the Equator: being reduced in the Northern Hemisphere but enhanced in the Southern Hemisphere. This is clearly driven by the altered seasonal insolation. Nonetheless, the enhanced seasonality drove localised changes in genesis potential, by altering the strength of monsoons and shifting the intertropical convergence zone. Trends in future tropical cyclone genesis potential are consistent neither between the five models studied nor with the palaeoclimate results. It is not clear why this should be the case. KW - lgm KW - midholocene KW - midpliocene KW - pliomip KW - pmip3 KW - tropics AU - Koh, JH AU - Brierley, CM PY - 2015/10/21/ UR - http://dx.doi.org/10.5194/cp-11-1433-2015 DO - doi: 10.5194/cp-11-1433-2015 ER - TY - JOUR ID - citeulike:13204324 L3 - citeulike-article-id:13204324 TI - {A} mid-Holocene climate reconstruction for eastern {S}outh {A}merica JF - Climate of the Past VL - 9 IS - 5 SP - 2117 EP - 2133 PB - Copernicus Publications N2 - The mid-Holocene (6000 calibrated years before present) is a key period in palaeoclimatology because incoming summer insolation was lower than during the late Holocene in the Southern Hemisphere, whereas the opposite happened in the Northern Hemisphere. However, the effects of the decreased austral summer insolation over South American climate have been poorly discussed by palaeodata syntheses. In addition, only a few of the regional studies have characterised the mid-Holocene climate in South America through a multiproxy approach. Here, we present a multiproxy compilation of mid-Holocene palaeoclimate data for eastern South America. We compiled 120 palaeoclimatological datasets, which were published in 84 different papers. The palaeodata analysed here suggest a water deficit scenario in the majority of eastern South America during the mid-Holocene if compared to the late Holocene, with the exception of northeastern Brazil. Low mid-Holocene austral summer insolation caused a reduced land–sea temperature contrast and hence a weakened South American monsoon system circulation. This scenario is represented by a decrease in precipitation over the South Atlantic Convergence Zone area, saltier conditions along the South American continental margin, and lower lake levels. KW - midholocene KW - pmip3 KW - reconstruction AU - Prado, LF AU - Wainer, I AU - Chiessi, CM AU - Ledru, MP AU - Turcq, B PY - 2013/09/09/ UR - http://dx.doi.org/10.5194/cp-9-2117-2013 DO - doi: 10.5194/cp-9-2117-2013 ER - TY - JOUR ID - citeulike:12707160 L3 - citeulike-article-id:12707160 TI - Mid-Holocene PMIP3/CMIP5 model results: Intercomparison for the South American Monsoon System JF - The Holocene VL - 23 IS - 12 SP - 1915 EP - 1920 PB - SAGE Publications SN - 1477-0911 N2 - The mean precipitation fields for eastern South America from eight mid-Holocene (6 ka) simulations, part of the third phase of Palaeoclimate Modeling Intercomparison Project (PMIP3) and the fifth phase of the Coupled Model Intercomparison Project (CMIP5), are evaluated. These simulations were compared to a new multiproxy compilation of 120 previously published records of changes in South American paleoclimate. Results show that when compared with modern conditions, mid-Holocene proxy data point to a drier Southern Brazil and South Atlantic Convergence Zone (SACZ), but a wetter/similar Northeastern Brazil. This suggests a weaker South American Monsoon System during the mid-Holocene when compared with its modern strength. All analyzed model simulations indicate a similar pattern, with a southward shift of the Intertropical Convergence Zone during the mid-Holocene, related to a weaker South Atlantic subtropical high, and negative annual precipitation anomalies over the SACZ area. Regional differences between the analyzed models were clearly detected. KW - cmip5 KW - midholocene KW - model_data_comparison KW - monsoon KW - pmip3 AU - Prado, Luciana AU - Wainer, Ilana AU - Chiessi, Cristiano PY - 2013/12/01/ UR - http://dx.doi.org/10.1177/0959683613505336 DO - doi: 10.1177/0959683613505336 ER - TY - JOUR ID - citeulike:12783132 L3 - citeulike-article-id:12783132 TI - {C}onsistency of the multi-model CMIP5/PMIP3-past1000 ensemble JF - Climate of the Past VL - 9 IS - 6 SP - 2471 EP - 2487 PB - Copernicus Publications N2 - We present an assessment of the probabilistic and climatological consistency of the CMIP5/PMIP3 ensemble simulations for the last millennium relative to proxy-based reconstructions under the paradigm of a statistically indistinguishable ensemble. We evaluate whether simulations and reconstructions are compatible realizations of the unknown past climate evolution. A lack of consistency is diagnosed in surface air temperature data for the Pacific, European and North Atlantic regions. On the other hand, indications are found that temperature signals partially agree in the western tropical Pacific, the subtropical North Pacific and the South Atlantic. Deviations from consistency may change between sub-periods, and they may include pronounced opposite biases in different sub-periods. These distributional inconsistencies originate mainly from differences in multi-centennial to millennial trends. Since the data uncertainties are only weakly constrained, the frequently too wide ensemble distributions prevent the formal rejection of consistency of the simulation ensemble. The presented multi-model ensemble consistency assessment gives results very similar to a previously discussed single-model ensemble suggesting that structural and parametric uncertainties do not exceed forcing and internal variability uncertainties. KW - cmip5 KW - past1000 KW - pmip3 AU - Bothe, O AU - Jungclaus, JH AU - Zanchettin, D PY - 2013/11/05/ UR - http://dx.doi.org/10.5194/cp-9-2471-2013 DO - doi: 10.5194/cp-9-2471-2013 ER - TY - JOUR ID - citeulike:13131100 L3 - citeulike-article-id:13131100 TI - LGM permafrost distribution: how well can the latest PMIP multi-model ensembles perform reconstruction? JF - Climate of the Past VL - 9 IS - 4 SP - 1697 EP - 1714 PB - Copernicus Publications N2 - Here, global-scale frozen ground distribution from the Last Glacial Maximum (LGM) has been reconstructed using multi-model ensembles of global climate models, and then compared with evidence-based knowledge and earlier numerical results. Modeled soil temperatures, taken from Paleoclimate Modelling Intercomparison Project phase III (PMIP3) simulations, were used to diagnose the subsurface thermal regime and determine underlying frozen ground types for the present day (pre-industrial; 0 kya) and the LGM (21 kya). This direct method was then compared to an earlier indirect method, which categorizes underlying frozen ground type from surface air temperature, applying to both the PMIP2 (phase II) and PMIP3 products. Both direct and indirect diagnoses for 0 kya showed strong agreement with the present-day observation-based map. The soil temperature ensemble showed a higher diversity around the border between permafrost and seasonally frozen ground among the models, partly due to varying subsurface processes, implementation, and settings. The area of continuous permafrost estimated by the PMIP3 multi-model analysis through the direct (indirect) method was 26.0 (17.7) million km2 for LGM, in contrast to 15.1 (11.2) million km2 for the pre-industrial control, whereas seasonally frozen ground decreased from 34.5 (26.6) million km2 to 18.1 (16.0) million km2. These changes in area resulted mainly from a cooler climate at LGM, but from other factors as well, such as the presence of huge land ice sheets and the consequent expansion of total land area due to sea-level change. LGM permafrost boundaries modeled by the PMIP3 ensemble – improved over those of the PMIP2 due to higher spatial resolutions and improved climatology – also compared better to previous knowledge derived from geomorphological and geocryological evidence. Combinatorial applications of coupled climate models and detailed stand-alone physical-ecological models for the cold-region terrestrial, paleo-, and modern climates will advance our understanding of the functionality and variability of the frozen ground subsystem in the global eco-climate system. KW - cmip5 KW - lgm KW - picontrol KW - pmip2 KW - pmip3 AU - Saito, K AU - Sueyoshi, T AU - Marchenko, S AU - Romanovsky, V AU - Otto-Bliesner, B AU - Walsh, J AU - Bigelow, N AU - Hendricks, A AU - Yoshikawa, K PY - 2013/08/01/ UR - http://dx.doi.org/10.5194/cp-9-1697-2013 DO - doi: 10.5194/cp-9-1697-2013 ER - TY - JOUR ID - citeulike:12397019 L3 - citeulike-article-id:12397019 TI - Large-scale temperature response to external forcing in simulations and reconstructions of the last millennium JF - Climate of the Past VL - 9 IS - 1 SP - 393 EP - 421 PB - Copernicus Publications N2 - Understanding natural climate variability and its driving factors is crucial to assessing future climate change. Therefore, comparing proxy-based climate reconstructions with forcing factors as well as comparing these with paleoclimate model simulations is key to gaining insights into the relative roles of internal versus forced variability. A review of the state of modelling of the climate of the last millennium prior to the CMIP5–PMIP3 (Coupled Model Intercomparison Project Phase 5–Paleoclimate Modelling Intercomparison Project Phase 3) coordinated effort is presented and compared to the available temperature reconstructions. Simulations and reconstructions broadly agree on reproducing the major temperature changes and suggest an overall linear response to external forcing on multidecadal or longer timescales. Internal variability is found to have an important influence at hemispheric and global scales. The spatial distribution of simulated temperature changes during the transition from the Medieval Climate Anomaly to the Little Ice Age disagrees with that found in the reconstructions. Thus, either internal variability is a possible major player in shaping temperature changes through the millennium or the model simulations have problems realistically representing the response pattern to external forcing. A last millennium transient climate response (LMTCR) is defined to provide a quantitative framework for analysing the consistency between simulated and reconstructed climate. Beyond an overall agreement between simulated and reconstructed LMTCR ranges, this analysis is able to single out specific discrepancies between some reconstructions and the ensemble of simulations. The disagreement is found in the cases where the reconstructions show reduced covariability with external forcings or when they present high rates of temperature change. KW - cmip5 KW - model_data_comparison KW - past1000 KW - pmip3 AU - Fernández-Donado, L AU - González-Rouco, JF AU - Raible, CC AU - Ammann, CM AU - Barriopedro, D AU - García-Bustamante, E AU - Jungclaus, JH AU - Lorenz, SJ AU - Luterbacher, J AU - Phipps, SJ AU - Servonnat, J AU - Swingedouw, D AU - Tett, SFB AU - Wagner, S AU - Yiou, P AU - Zorita, E PY - 2013/02/14/ UR - http://dx.doi.org/10.5194/cp-9-393-2013 DO - doi: 10.5194/cp-9-393-2013 ER - TY - JOUR ID - citeulike:13131106 L3 - citeulike-article-id:13131106 TI - {E}valuation of modern and mid-Holocene seasonal precipitation of the {M}editerranean and northern {A}frica in the CMIP5 simulations JF - Climate of the Past VL - 10 IS - 2 SP - 551 EP - 568 PB - Copernicus Publications N2 - We analyse the spatial expression of seasonal climates of the Mediterranean and northern Africa in pre-industrial (piControl) and mid-Holocene (midHolocene, 6 yr BP) simulations from the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Modern observations show four distinct precipitation regimes characterized by differences in the seasonal distribution and total amount of precipitation: an equatorial band characterized by a double peak in rainfall, the monsoon zone characterized by summer rainfall, the desert characterized by low seasonality and total precipitation, and the Mediterranean zone characterized by summer drought. Most models correctly simulate the position of the Mediterranean and the equatorial climates in the piControl simulations, but overestimate the extent of monsoon influence and underestimate the extent of desert. However, most models fail to reproduce the amount of precipitation in each zone. Model biases in the simulated magnitude of precipitation are unrelated to whether the models reproduce the correct spatial patterns of each regime. In the midHolocene, the models simulate a reduction in winter rainfall in the equatorial zone, and a northward expansion of the monsoon with a significant increase in summer and autumn rainfall. Precipitation is slightly increased in the desert, mainly in summer and autumn, with northward expansion of the monsoon. Changes in the Mediterranean are small, although there is an increase in spring precipitation consistent with palaeo-observations of increased growing-season rainfall. Comparison with reconstructions shows most models underestimate the mid-Holocene changes in annual precipitation, except in the equatorial zone. Biases in the piControl have only a limited influence on midHolocene anomalies in ocean–atmosphere models; carbon-cycle models show no relationship between piControl bias and midHolocene anomalies. Biases in the prediction of the midHolocene monsoon expansion are unrelated to how well the models simulate changes in Mediterranean climate. KW - cmip5 KW - historical KW - midholocene KW - model_data_comparison KW - picontrol KW - pmip3 AU - Perez-Sanz, A AU - Li, G AU - González-Sampériz, P AU - Harrison, SP PY - 2014/03/20/ UR - http://dx.doi.org/10.5194/cp-10-551-2014 DO - doi: 10.5194/cp-10-551-2014 ER - TY - JOUR ID - citeulike:12963286 L3 - citeulike-article-id:12963286 TI - {U}sing palaeo-climate comparisons to constrain future projections in CMIP5 JF - Climate of the Past VL - 10 IS - 1 SP - 221 EP - 250 PB - Copernicus Publications N2 - We present a selection of methodologies for using the palaeo-climate model component of the Coupled Model Intercomparison Project (Phase 5) (CMIP5) to attempt to constrain future climate projections using the same models. The constraints arise from measures of skill in hindcasting palaeo-climate changes from the present over three periods: the Last Glacial Maximum (LGM) (21 000 yr before present, ka), the mid-Holocene (MH) (6 ka) and the Last Millennium (LM) (850–1850 CE). The skill measures may be used to validate robust patterns of climate change across scenarios or to distinguish between models that have differing outcomes in future scenarios. We find that the multi-model ensemble of palaeo-simulations is adequate for addressing at least some of these issues. For example, selected benchmarks for the LGM and MH are correlated to the rank of future projections of precipitation/temperature or sea ice extent to indicate that models that produce the best agreement with palaeo-climate information give demonstrably different future results than the rest of the models. We also explore cases where comparisons are strongly dependent on uncertain forcing time series or show important non-stationarity, making direct inferences for the future problematic. Overall, we demonstrate that there is a strong potential for the palaeo-climate simulations to help inform the future projections and urge all the modelling groups to complete this subset of the CMIP5 runs. KW - 1pctco2 KW - abrupt4xco2 KW - cmip5 KW - historical KW - lgm KW - midholocene KW - model_data_comparison KW - past1000 KW - picontrol KW - pmip2 KW - pmip3 AU - Schmidt, GA AU - Annan, JD AU - Bartlein, PJ AU - Cook, BI AU - Guilyardi, E AU - Hargreaves, JC AU - Harrison, SP AU - Kageyama, M AU - LeGrande, AN AU - Konecky, B AU - Lovejoy, S AU - Mann, ME AU - Masson-Delmotte, V AU - Risi, C AU - Thompson, D AU - Timmermann, A AU - Tremblay, LB AU - Yiou, P PY - 2014/02/05/ UR - http://dx.doi.org/10.5194/cp-10-221-2014 DO - doi: 10.5194/cp-10-221-2014 ER - TY - JOUR ID - citeulike:13131109 L3 - citeulike-article-id:13131109 TI - {S}outhern westerlies in LGM and future (RCP4.5) climates JF - Climate of the Past VL - 9 IS - 2 SP - 517 EP - 524 PB - Copernicus Publications N2 - Mid-latitude westerlies are a major component of the atmospheric circulation and understanding their behaviour under climate change is important for understanding changes in precipitation, storms and atmosphere–ocean momentum, heat and CO2 exchanges. The Southern Hemisphere westerlies have been particularly studied in terms of the latter aspects, since the Southern Ocean is a key region for the global oceanic circulation as well as for CO2 uptake. In this study, we analyse, mainly in terms of jet stream position, the behaviour of the southern westerlies for the Last Glacial Maximum (LGM, 21 000 yr ago, which is the last past cold extreme) and for a future climate, obtained after stabilisation of the RCP4.5 scenario. The a priori guess would be that the behaviour of the westerly jet stream would be similar when examining its changes from LGM to pre-industrial (PI) conditions and from PI to RCP4.5, i.e. in both cases a poleward shift in response to global warming. We show that this is in fact not the case, due to the impact of altitude changes of the Antarctic ice sheet and/or to sea ice cover changes. KW - cmip5 KW - lgm KW - picontrol KW - pmip3 KW - rcp45 AU - Chavaillaz, Y AU - Codron, F AU - Kageyama, M PY - 2013/03/01/ UR - http://dx.doi.org/10.5194/cp-9-517-2013 DO - doi: 10.5194/cp-9-517-2013 ER - TY - JOUR ID - citeulike:12186879 L3 - citeulike-article-id:12186879 TI - {S}kill and reliability of climate model ensembles at the {L}ast {G}lacial {M}aximum and mid-Holocene JF - Climate of the Past VL - 9 IS - 2 SP - 811 EP - 823 PB - Copernicus Publications N2 - Paleoclimate simulations provide us with an opportunity to critically confront and evaluate the performance of climate models in simulating the response of the climate system to changes in radiative forcing and other boundary conditions. Hargreaves et al. (2011) analysed the reliability of the Paleoclimate Modelling Intercomparison Project, PMIP2 model ensemble with respect to the MARGO sea surface temperature data synthesis (MARGO Project Members, 2009) for the Last Glacial Maximum (LGM, 21 ka BP). Here we extend that work to include a new comprehensive collection of land surface data (Bartlein et al., 2011), and introduce a novel analysis of the predictive skill of the models. We include output from the PMIP3 experiments, from the two models for which suitable data are currently available. We also perform the same analyses for the PMIP2 mid-Holocene (6 ka BP) ensembles and available proxy data sets.

Our results are predominantly positive for the LGM, suggesting that as well as the global mean change, the models can reproduce the observed pattern of change on the broadest scales, such as the overall land–sea contrast and polar amplification, although the more detailed sub-continental scale patterns of change remains elusive. In contrast, our results for the mid-Holocene are substantially negative, with the models failing to reproduce the observed changes with any degree of skill. One cause of this problem could be that the globally- and annually-averaged forcing anomaly is very weak at the mid-Holocene, and so the results are dominated by the more localised regional patterns in the parts of globe for which data are available. The root cause of the model-data mismatch at these scales is unclear. If the proxy calibration is itself reliable, then representativity error in the data-model comparison, and missing climate feedbacks in the models are other possible sources of error. KW - cmip5 KW - lgm KW - midholocene KW - model_data_comparison KW - pmip2 KW - pmip3 AU - Hargreaves, JC AU - Annan, JD AU - Ohgaito, R AU - Paul, A AU - Abe-Ouchi, A PY - 2013/03/21/ UR - http://dx.doi.org/10.5194/cp-9-811-2013 DO - doi: 10.5194/cp-9-811-2013 ER - TY - JOUR ID - citeulike:12272600 L3 - citeulike-article-id:12272600 TI - {T}he sensitivity of the {A}rctic sea ice to orbitally induced insolation changes: a study of the mid-Holocene {P}aleoclimate {M}odelling {I}ntercomparison {P}roject 2 and 3 simulations JF - Climate of the Past VL - 9 IS - 2 SP - 969 EP - 982 PB - Copernicus Publications N2 - In the present work the Arctic sea ice in the mid-Holocene and the pre-industrial climates are analysed and compared on the basis of climate-model results from the Paleoclimate Modelling Intercomparison Project phase 2 (PMIP2) and phase 3 (PMIP3). The PMIP3 models generally simulate smaller and thinner sea-ice extents than the PMIP2 models both for the pre-industrial and the mid-Holocene climate. Further, the PMIP2 and PMIP3 models all simulate a smaller and thinner Arctic summer sea-ice cover in the mid-Holocene than in the pre-industrial control climate. The PMIP3 models also simulate thinner winter sea ice than the PMIP2 models. The winter sea-ice extent response, i.e. the difference between the mid-Holocene and the pre-industrial climate, varies among both PMIP2 and PMIP3 models. Approximately one half of the models simulate a decrease in winter sea-ice extent and one half simulates an increase. The model-mean summer sea-ice extent is 11 % (21 %) smaller in the mid-Holocene than in the pre-industrial climate simulations in the PMIP2 (PMIP3). In accordance with the simple model of Thorndike (1992), the sea-ice thickness response to the insolation change from the pre-industrial to the mid-Holocene is stronger in models with thicker ice in the pre-industrial climate simulation. Further, the analyses show that climate models for which the Arctic sea-ice responses to increasing atmospheric CO2 concentrations are similar may simulate rather different sea-ice responses to the change in solar forcing between the mid-Holocene and the pre-industrial. For two specific models, which are analysed in detail, this difference is found to be associated with differences in the simulated cloud fractions in the summer Arctic; in the model with a larger cloud fraction the effect of insolation change is muted. A sub-set of the mid-Holocene simulations in the PMIP ensemble exhibit open water off the north-eastern coast of Greenland in summer, which can provide a fetch for surface waves. This is in broad agreement with recent analyses of sea-ice proxies, indicating that beach-ridges formed on the north-eastern coast of Greenland during the early- to mid-Holocene. KW - cmip5 KW - midholocene KW - picontrol KW - pmip2 KW - pmip3 AU - Berger, M AU - Brandefelt, J AU - Nilsson, J PY - 2013/04/15/ UR - http://dx.doi.org/10.5194/cp-9-969-2013 DO - doi: 10.5194/cp-9-969-2013 ER - TY - JOUR ID - citeulike:13132317 L3 - citeulike-article-id:13132317 TI - Sensitivity of Southern Hemisphere circulation to LGM and 4 × CO2 climates JF - Geophys. Res. Lett. VL - 40 IS - 5 SP - 965 EP - 970 SN - 00948276 N2 - This paper investigates the effect of Last Glacial Maximum (LGM) versus high CO2 world boundary condition on the Southern Hemisphere atmospheric circulation, in particular on the strength and latitudinal position of the near surface Southern Westerly Winds (SWW). PMIP2 and PMIP3 experiments, as well as the “abrupt 4 × CO2” simulations from CMIP5, were analyzed. Robust findings include poleward expansion of the Mean Meridional Circulation (MMC) and intensified and poleward-shifted SWW in the 4 × CO2 simulations (consistent with recent observations and 21st century climate change projections); and for the LGM, stronger and southward shifted northern hemisphere MMC, and weakened southern Hadley cell. However, six of the eight LGM simulations show a decrease in the SWW, the other two models simulate the opposite. A critical difference between the models is strong coupling between sea-ice extent, surface temperature gradients, SWW, and Ferrel cell in the two models with stronger and poleward-shifted SWW. KW - abrupt4xco2 KW - cmip5 KW - lgm KW - picontrol KW - pmip3 AU - Rojas, M PY - 2013/03/16/ UR - http://dx.doi.org/10.1002/grl.50195 DO - doi: 10.1002/grl.50195 ER - TY - JOUR ID - citeulike:12614193 L3 - citeulike-article-id:12614193 TI - Stationarity of the tropical pacific teleconnection to North America in CMIP5/PMIP3 model simulations JF - Geophysical Research Letters VL - 40 IS - 18 SP - 4927 EP - 4932 SN - 00948276 N2 - The temporal stationarity of the teleconnection between the tropical Pacific Ocean and North America (NA) is analyzed in atmosphere-only, and coupled last-millennium, historical, and control runs from the Coupled Model Intercomparison Project Phase 5 data archive. The teleconnection, defined as the correlation between December-January-February (DJF) tropical Pacific sea surface temperatures (SSTs) and DJF 200 mb geopotential height, is found to be nonstationary on multidecadal timescales. There are significant changes in the spatial features of the teleconnection over NA in continuous 56-year segments of the last millennium and control simulations. Analysis of atmosphere-only simulations forced with observed SSTs indicates that atmospheric noise cannot account for the temporal variability of the teleconnection, which instead is likely explained by the strength of, and multidecadal changes in, tropical Pacific Ocean variability. These results have implications for teleconnection-based analyses of model fidelity in simulating precipitation, as well as any reconstruction and forecasting efforts that assume stationarity of the observed teleconnection. KW - cmip5 KW - historical KW - past1000 KW - picontrol KW - pmip3 AU - Coats, Sloan AU - Smerdon, Jason AU - Cook, Benjamin AU - Seager, Richard PY - 2013/09/28/ UR - http://dx.doi.org/10.1002/grl.50938 DO - doi: 10.1002/grl.50938 ER - TY - JOUR ID - citeulike:11436956 L3 - citeulike-article-id:11436956 TI - {C}onstraining the temperature history of the past millennium using early instrumental observations JF - Climate of the Past VL - 8 IS - 5 SP - 1551 EP - 1563 PB - Copernicus Publications N2 - The current assessment that twentieth-century global temperature change is unusual in the context of the last thousand years relies on estimates of temperature changes from natural proxies (tree-rings, ice-cores, etc.) and climate model simulations. Confidence in such estimates is limited by difficulties in calibrating the proxies and systematic differences between proxy reconstructions and model simulations. As the difference between the estimates extends into the relatively recent period of the early nineteenth century it is possible to compare them with a reliable instrumental estimate of the temperature change over that period, provided that enough early thermometer observations, covering a wide enough expanse of the world, can be collected.

One organisation which systematically made observations and collected the results was the English East India Company (EEIC), and their archives have been preserved in the British Library. Inspection of those archives revealed 900 log-books of EEIC ships containing daily instrumental measurements of temperature and pressure, and subjective estimates of wind speed and direction, from voyages across the Atlantic and Indian Oceans between 1789 and 1834. Those records have been extracted and digitised, providing 273 000 new weather records offering an unprecedentedly detailed view of the weather and climate of the late eighteenth and early nineteenth centuries.

The new thermometer observations demonstrate that the large-scale temperature response to the Tambora eruption and the 1809 eruption was modest (perhaps 0.5 °C). This provides an out-of-sample validation for the proxy reconstructions – supporting their use for longer-term climate reconstructions. However, some of the climate model simulations in the CMIP5 ensemble show much larger volcanic effects than this – such simulations are unlikely to be accurate in this respect. KW - cmip5 KW - model_data_comparison KW - past1000 KW - pmip3 KW - reconstruction AU - Brohan, P AU - Allan, R AU - Freeman, E AU - Wheeler, D AU - Wilkinson, C AU - Williamson, F PY - 2012/10/11/ UR - http://dx.doi.org/10.5194/cp-8-1551-2012 DO - doi: 10.5194/cp-8-1551-2012 ER - TY - JOUR ID - citeulike:12447013 L3 - citeulike-article-id:12447013 TI - Set-up of the PMIP3 paleoclimate experiments conducted using an {E}arth system model, MIROC-ESM JF - Geoscientific Model Development VL - 6 IS - 3 SP - 819 EP - 836 PB - Copernicus Publications N2 - Paleoclimate experiments using contemporary climate models are an effective measure to evaluate climate models. In recent years, Earth system models (ESMs) were developed to investigate carbon cycle climate feedbacks, as well as to project the future climate. Paleoclimate events can be suitable benchmarks to evaluate ESMs. The variation in aerosols associated with the volcanic eruptions provide a clear signal in forcing, which can be a good test to check the response of a climate model to the radiation changes. The variations in atmospheric CO2 level or changes in ice sheet extent can be used for evaluation as well. Here we present implementations of the paleoclimate experiments proposed by the Coupled Model Intercomparison Project phase 5/Paleoclimate Modelling Intercomparison Project phase 3 (CMIP5/PMIP3) using MIROC-ESM, an ESM based on the global climate model MIROC (Model for Interdisciplinary Research on Climate). In this paper, experimental settings and spin-up procedures of the mid-Holocene, the Last Glacial Maximum, and the Last Millennium experiments are explained. The first two experiments are time slice experiments and the last one is a transient experiment. The complexity of the model requires various steps to correctly configure the experiments. Several basic outputs are also shown. KW - cmip5 KW - lgm KW - midholocene KW - miroc_model KW - past1000 KW - pmip3 AU - Sueyoshi, T AU - Ohgaito, R AU - Yamamoto, A AU - Chikamoto, MO AU - Hajima, T AU - Okajima, H AU - Yoshimori, M AU - Abe, M AU - O'ishi, R AU - Saito, F AU - Watanabe, S AU - Kawamiya, M AU - Abe-Ouchi, A PY - 2013/06/21/ UR - http://dx.doi.org/10.5194/gmd-6-819-2013 DO - doi: 10.5194/gmd-6-819-2013 ER - TY - JOUR ID - citeulike:13132455 L3 - citeulike-article-id:13132455 TI - Sensitivity to Glacial Forcing in the CCSM4 JF - Journal of Climate VL - 26 IS - 6 SP - 1901 EP - 1925 KW - cmip5 KW - lgm KW - model_data_comparison KW - ncar_model KW - picontrol KW - pmip3 AU - Brady, Esther AU - Otto-Bliesner, Bette AU - Kay, Jennifer AU - Rosenbloom, Nan PY - 2013/03// ER - TY - JOUR ID - citeulike:12527603 L3 - citeulike-article-id:12527603 TI - Mid-Holocene tropical Pacific climate state, annual cycle, and ENSO in PMIP2 and PMIP3 T2 - Climate Dynamics JF - Climate Dynamics VL - 43 IS - 3-4 SP - 957 EP - 970 PB - Springer Berlin Heidelberg N2 - Using the Paleoclimate Modeling Inter-comparison Project Phase 2 and 3 (PMIP2 and PMIP3), we investigated the tropical Pacific climate state, annual cycle, and El Niño-Southern Oscillation (ENSO) during the mid-Holocene period (6,000 years before present; 6 ka run). When the 6 ka run was compared to the control run (0 ka run), the reduced sea surface temperature (SST) and the reduced precipitation due to the basin-wide cooling, and the intensified cross-equatorial surface winds due to the hemispheric discrepancy of the surface cooling over the tropical Pacific were commonly observed in both the PMIP2 and PMIP3, but changes were more dominant in the PMIP3. The annual cycle of SST was weaker over the equatorial eastern Pacific, because of the orbital forcing change and the deepening mixed layer, while it was stronger over the equatorial western pacific in both the PMIP2 and PMIP3. The stronger annual cycle of the equatorial western Pacific SST was accompanied by the intensified annual cycle of the zonal surface wind, which dominated in the PMIP3 in particular. The ENSO activity in the 6 ka run was significantly suppressed in the PMIP2, but marginally reduced in the PMIP3. In general, the weakened air-sea coupling associated with basin-wide cooling, reduced precipitation, and a hemispheric contrast in the climate state led to the suppression of ENSO activity, and the weakening of the annual cycle over the tropical eastern Pacific might lead to the intensification of ENSO through the frequency entrainment. Therefore, the two opposite effects are slightly compensated for by each other, which results in a small reduction in the ENSO activity during the 6 ka in the PMIP3. On the whole, in PMIP2/PMIP3, the variability of canonical (or conventional) El Niño tends to be reduced during 6 ka, while that of CP/Modoki El Niño tends to be intensified. KW - cmip5 KW - enso KW - midholocene KW - picontrol KW - pmip2 KW - pmip3 AU - An, Soon-Il AU - Choi, Jung PY - 2014/// UR - http://dx.doi.org/10.1007/s00382-013-1880-z DO - doi: 10.1007/s00382-013-1880-z ER - TY - JOUR ID - citeulike:13132468 L3 - citeulike-article-id:13132468 TI - Ocean Cooling Pattern at the Last Glacial Maximum JF - Advances in Meteorology VL - 2012 SP - 1 EP - 8 SN - 1687-9309 KW - cmip5 KW - lgm KW - picontrol KW - pmip3 AU - Zhuang, Kelin AU - Giardino, John PY - 2012/// UR - http://dx.doi.org/10.1155/2012/213743 DO - doi: 10.1155/2012/213743 ER - TY - JOUR ID - citeulike:13132476 L3 - citeulike-article-id:13132476 TI - Modelling past sea ice changes JF - Quaternary Science Reviews VL - 79 SP - 191 EP - 206 SN - 02773791 KW - cmip5 KW - lgm KW - midholocene KW - model_data_comparison KW - past1000 KW - picontrol KW - pmip2 KW - pmip3 AU - Goosse, H AU - Roche, DM AU - Mairesse, A AU - Berger, M PY - 2013/11// UR - http://dx.doi.org/10.1016/j.quascirev.2013.03.011 DO - doi: 10.1016/j.quascirev.2013.03.011 ER - TY - JOUR ID - citeulike:11870681 L3 - citeulike-article-id:11870681 TI - Mid-Holocene East Asian summer monsoon strengthening: Insights from Paleoclimate Modeling Intercomparison Project (PMIP) simulations JF - Palaeogeography, Palaeoclimatology, Palaeoecology VL - 369 SP - 422 EP - 429 SN - 00310182 N2 - The East Asian summer (June–July–August) monsoon (EASM) is typically thought to have been stronger during interglacial periods based on spatially sparse proxy data. On a large scale, however, whether this view is true and if so, its underlying dynamic mechanisms remain unclear. Using all pertinent experiments within the Paleoclimate Modeling Intercomparison Project (PMIP), here we present an analysis of the EASM during the mid-Holocene, 6000 years ago. Supporting the paleodata, the mid-Holocene EASM, as measured by regionally averaged meridional wind at 850 hPa, became stronger than the baseline period in 27 out of 28 PMIP models with a demonstrable ability to simulate the modern EASM climatology. On average, the EASM strengthened by 32% across all the models and by a larger magnitude in 23 coupled models (35%) than in five atmospheric models (20%). It is proposed that an enhanced land–sea thermal contrast, and hence sea level pressure gradient, between the East Asian continent and adjacent oceans as a result of orbital forcing was responsible for the EASM strengthening during the mid-Holocene. ► We examined the mid-Holocene East Asian summer monsoon using results of 28 models. ► The mid-Holocene East Asian summer monsoon strengthened on average by 32%. ► An enhanced land–sea thermal contrast was found to be the reason. ► The simulations support the paleodata. KW - cmip5 KW - midholocene KW - monsoon KW - picontrol KW - pmip2 KW - pmip3 AU - Jiang, Dabang AU - Lang, Xianmei AU - Tian, Zhiping AU - Ju, Lixia PY - 2013/01// UR - http://dx.doi.org/10.1016/j.palaeo.2012.11.007 DO - doi: 10.1016/j.palaeo.2012.11.007 ER - TY - JOUR ID - citeulike:12727428 L3 - citeulike-article-id:12727428 TI - Drawbacks to palaeodistribution modelling: the case of South American seasonally dry forests JF - Journal of Biogeography VL - 40 IS - 2 SP - 345 EP - 358 SN - 03050270 N2 - Aim Species distribution modelling (SDM) has increasingly been used to predict palaeodistributions at regional and global scales in order to understand the response of vegetation to climate change and to estimate palaeodistributions for the testing of biogeographical hypotheses. However, there are many sources of uncertainty in SDM that may restrict the ability of models to hindcast palaeo-distributions and provide a basis for hypothesis testing in molecular phylogenetics and phylogeographical studies. Location Seasonally dry forests (SDFs) in South America. Methods We addressed the problem of using palaeodistribution modelling for SDFs based on the projection of their current distribution into past environments (21 ka) using 11 methods for SDMs and five coupled atmosphere–ocean global circulation models (AOGCMs) for 16 species. Results We observed considerable uncertainty in the hindcasts, with the most important effects for AOGCM (median 12.2%), species (median 15.6%) and their interaction (median 13.6%). The effects of AOGCMs were stronger in the Amazon region, whereas the species effect occurred primarily in the dry areas of central Brazil. The log-linear model detected significant effects of the three sources of variation and their interaction on the classification of each map in supporting alternative hypotheses. An expansion scenario combining the Pleistocene arc and Amazonian expansion, and Pennington's Amazonian expansion alone, were the most frequently supported palaeodistribution scenarios. Main conclusions As a basis for evaluating a given hypothesis, hindcast distributions must be used in direct association with other evidence, such as molecular variation and the fossil record. We propose an alternative framework concerning hypothesis testing that couples SDM and phylogeographical work, in which palaeoclimatic distributions and other sources of information, such as the pollen fossil record and coalescence modelling, must be weighted equally. KW - cmip5 KW - lgm KW - picontrol KW - pmip3 AU - Collevatti, Rosane AU - Terribile, Levi AU - de Oliveira, Guilherme AU - Lima-Ribeiro, Matheus AU - Nabout, João AU - Rangel, Thiago AU - Diniz-Filho, Jose PY - 2013/02/01/ UR - http://dx.doi.org/10.1111/jbi.12005 DO - doi: 10.1111/jbi.12005 ER - TY - JOUR ID - citeulike:13132786 L3 - citeulike-article-id:13132786 TI - A coupled phylogeographical and species distribution modelling approach recovers the demographical history of a Neotropical seasonally dry forest tree species JF - Molecular Ecology VL - 21 IS - 23 SP - 5845 EP - 5863 SN - 09621083 KW - cmip5 KW - lgm KW - picontrol KW - pmip3 AU - Collevatti, Rosane AU - Terribile, Levi AU - Lima-Ribeiro, Matheus AU - Nabout, João AU - de Oliveira, Guilherme AU - Rangel, Thiago AU - Rabelo, Suelen AU - Diniz-Filho, Jose PY - 2012/12// UR - http://dx.doi.org/10.1111/mec.12071 DO - doi: 10.1111/mec.12071 ER - TY - JOUR ID - citeulike:13132797 L3 - citeulike-article-id:13132797 TI - Modelando a distribuição geográfica das espécies no passado: uma abordagem promissora em Paleoecologia JF - REVISTA BRASILEIRA DE PALEONTOLOGIA VL - 15 IS - 03 SP - 371 EP - 385 SN - 15197530 KW - cmip5 KW - lgm KW - midholocene KW - pmip2 KW - pmip3 AU - Lima-Ribeiro, Matheus AU - Diniz-Filho, José PY - 2012/12/31/ UR - http://dx.doi.org/10.4072/rbp.2012.3.12 DO - doi: 10.4072/rbp.2012.3.12 ER - TY - JOUR ID - citeulike:13132813 L3 - citeulike-article-id:13132813 TI - {M}ismatch between the depth habitat of planktonic foraminifera and the calibration depth of SST transfer functions may bias reconstructions JF - Climate of the Past VL - 9 IS - 2 SP - 859 EP - 870 PB - Copernicus Publications N2 - We demonstrate that the temperature signal in the planktonic foraminifera assemblage data from the North Atlantic typically does not originate from near-surface waters and argue that this has the potential to bias sea surface temperature reconstructions using transfer functions calibrated against near-surface temperatures if the thermal structure of the upper few hundred metres of ocean changes over time. CMIP5 climate models indicate that ocean thermal structure in the North Atlantic changed between the Last Glacial Maximum (LGM) and the pre-industrial (PI), with some regions, mainly in the tropics, of the LGM ocean lacking good thermal analogues in the PI.

Transfer functions calibrated against different depths reconstruct a marked subsurface cooling in parts of the tropical North Atlantic during the last glacial, in contrast to previous studies that reconstruct only a modest cooling. These possible biases in temperature reconstructions may affect estimates of climate sensitivity based on the difference between LGM and pre-industrial climate. Quantifying these biases has the potential to alter our understanding of LGM climate and improve estimates of climate sensitivity. KW - cmip5 KW - lgm KW - picontrol KW - pmip3 KW - reconstruction AU - Telford, RJ AU - Li, C AU - Kucera, M PY - 2013/03/22/ UR - http://dx.doi.org/10.5194/cp-9-859-2013 DO - doi: 10.5194/cp-9-859-2013 ER - TY - JOUR ID - citeulike:13132818 L3 - citeulike-article-id:13132818 TI - Areas of climate stability of species ranges in the Brazilian Cerrado: disentangling uncertainties through time JF - Natureza & Conservação VL - 10 IS - 2 SP - 152 EP - 159 SN - 16790073 KW - cmip5 KW - lgm KW - picontrol KW - pmip3 KW - rcp60 AU - Terribile, Levi PY - 2012/// UR - http://dx.doi.org/10.4322/natcon.2012.025 DO - doi: 10.4322/natcon.2012.025 ER - TY - JOUR ID - citeulike:12783316 L3 - citeulike-article-id:12783316 TI - Mid-Holocene net precipitation changes over China: model–data comparison JF - Quaternary Science Reviews VL - 82 SP - 104 EP - 120 SN - 02773791 KW - cmip5 KW - midholocene KW - monsoon KW - pmip3 AU - Jiang, Dabang AU - Tian, Zhiping AU - Lang, Xianmei PY - 2013/12// UR - http://dx.doi.org/10.1016/j.quascirev.2013.10.017 DO - doi: 10.1016/j.quascirev.2013.10.017 ER - TY - JOUR ID - citeulike:13132840 L3 - citeulike-article-id:13132840 TI - {M}id-Holocene ocean and vegetation feedbacks over {E}ast {A}sia JF - Climate of the Past VL - 9 IS - 5 SP - 2153 EP - 2171 PB - Copernicus Publications N2 - Mid-Holocene ocean and vegetation feedbacks over East Asia are investigated by a set of numerical experiments performed with the version 4 of the Community Climate System Model (CCSM4). With reference to the pre-industrial period, most of the mid-Holocene annual and seasonal surface-air temperature and precipitation changes are found to result from a direct response of the atmosphere to insolation forcing, while dynamic ocean and vegetation modulate regional climate of East Asia to some extent. Because of its thermal inertia, the dynamic ocean induced an additional warming of 0.2 K for the annual mean, 0.5 K in winter (December–February), 0.0003 K in summer (June–August), and 1.0 K in autumn (September–November), but a cooling of 0.6 K in spring (March–May) averaged over China, and it counteracted (amplified) the direct effect of insolation forcing for the annual mean and in winter and autumn (spring) for that period. The dynamic vegetation had an area-average impact of no more than 0.4 K on the mid-Holocene annual and seasonal temperatures over China, with an average cooling of 0.2 K for the annual mean. On the other hand, ocean feedback induced a small increase of precipitation in winter (0.04 mm day−1) and autumn (0.05 mm day−1), but a reduction for the annual mean (0.14 mm day−1) and in spring (0.29 mm day−1) and summer (0.34 mm day−1) over China, while it also suppressed the East Asian summer monsoon rainfall. The effect of dynamic vegetation on the mid-Holocene annual and seasonal precipitation was comparatively small, ranging from −0.03 mm day−1 to 0.06 mm day−1 averaged over China. In comparison, the CCSM4 simulated annual and winter cooling over China agrees with simulations within the Paleoclimate Modeling Intercomparison Project (PMIP), but the results are contrary to the warming reconstructed from multiple proxy data for the mid-Holocene. Ocean feedback narrows this model–data mismatch, whereas vegetation feedback plays an opposite role but with a level of uncertainty. KW - cmip5 KW - midholocene KW - ncar_model KW - picontrol KW - pmip3 AU - Tian, Z AU - Jiang, D PY - 2013/09/13/ UR - http://dx.doi.org/10.5194/cp-9-2153-2013 DO - doi: 10.5194/cp-9-2153-2013 ER - TY - JOUR ID - citeulike:12409822 L3 - citeulike-article-id:12409822 TI - Separating Forced from Chaotic Climate Variability over the Past Millennium JF - J. Climate VL - 26 IS - 18 SP - 6954 EP - 6973 PB - American Meteorological Society N2 - AbstractReconstructions of past climate show notable temperature variability over the past millennium, with relatively warm conditions during the Medieval Climate Anomaly (MCA) and a relatively cold Little Ice Age (LIA). Multimodel simulations of the past millennium are used together with a wide range of reconstructions of Northern Hemispheric mean annual temperature to separate climate variability from 850 to 1950 CE into components attributable to external forcing and internal climate variability. External forcing is found to contribute significantly to long-term temperature variations irrespective of the proxy reconstruction, particularly from 1400 onward. Over the MCA alone, however, the effect of forcing is only detectable in about half of the reconstructions considered, and the response to forcing in the models cannot explain the warm conditions around 1000 CE seen in some reconstructions. The residual from the detection analysis is used to estimate internal variability independent from climate modeling, and it is found that the recent observed 50- and 100-yr hemispheric temperature trends are substantially larger than any of the internally generated trends even using the large residuals over the MCA. Variations in solar output and explosive volcanism are found to be the main drivers of climate change from 1400 to 1900, but for the first time a significant contribution from greenhouse gas variations to the cold conditions during 1600?1800 is also detected. The proxy reconstructions tend to show a smaller forced response than is simulated by the models. This discrepancy is shown, at least partly, to be likely associated with the difference in the response to large volcanic eruptions between reconstructions and model simulations. KW - cmip5 KW - past1000 KW - pmip3 AU - Schurer, Andrew AU - Hegerl, Gabriele AU - Mann, Michael AU - Tett, Simon AU - Phipps, Steven PY - 2013/03/25/ UR - http://dx.doi.org/10.1175/jcli-d-12-00826.1 DO - doi: 10.1175/jcli-d-12-00826.1 ER - TY - JOUR ID - citeulike:13132463 L3 - citeulike-article-id:13132463 TI - Paleoclimate simulations of the mid-Holocene and last glacial maximum by FGOALS T2 - Advances in Atmospheric Sciences JF - Advances in Atmospheric Sciences VL - 30 IS - 3 SP - 684 EP - 698 PB - SP Science Press N2 - Paleoclimate simulations of the mid-Holocene (MH) and Last Glacial maximum (LGM) by the latest versions of the Flexible Global Ocean-Atmosphere-Land System model, Spectral Version 2 and Grid-point Version 2 (FGOALS-s2 and g2) are evaluated in this study. The MH is characterized by changes of insolation induced by orbital parameters, and the LGM is a glacial period with large changes in greenhouse gases, sea level and ice sheets. For the MH, both versions of FGOALS simulate reasonable responses to the changes of insolation, such as the enhanced summer monsoon in African-Asian regions. Model differences can be identified at regional and seasonal scales. The global annual mean surface air temperature (TAS) shows no significant change in FGOALS-s2, while FGOALS-g2 shows a global cooling of about 0.7°C that is related with a strong cooling during boreal winter. The amplitude of ENSO is weaker in FGOALS-g2, which agrees with proxy data. For the LGM, FGOALS-g2 captures the features of the cold and dry glacial climate, including a global cooling of 4.6°C and a decrease in precipitation by 10%. The ENSO is weaker at the LGM, with a tendency of stronger ENSO cold events. Sensitivity analysis shows that the Equilibrium Climate Sensitivity (ECS) estimated for FGOALS ranges between 4.23°C and 4.59°C. The sensitivity of precipitation to the changes of TAS is ∼2.3% °C−1, which agrees with previous studies. FGOALS-g2 shows better simulations of the Atlantic Meridional Overturning Circulation (AMOC) and African summer monsoon precipitation in the MH when compared with FGOALS-g1.0; however, it is hard to conclude any improvements for the LGM. KW - cmip5 KW - fgoals_model KW - lgm KW - midholocene KW - pmip3 AU - Zheng, Weipeng AU - Yu, Yongqiang PY - 2013/// UR - http://dx.doi.org/10.1007/s00376-012-2177-6 DO - doi: 10.1007/s00376-012-2177-6 ER - TY - JOUR ID - citeulike:12397020 L3 - citeulike-article-id:12397020 TI - {T}he {E}ast {A}sian {S}ummer {M}onsoon at mid-Holocene: results from PMIP3 simulations JF - Climate of the Past VL - 9 IS - 1 SP - 453 EP - 466 PB - Copernicus Publications N2 - Ten Coupled General Circulation Models (CGCMs) participated in the third phase of Paleoclimate Modelling Intercomparison Project (PMIP3) are assessed for the East Asian Summer Monsoon (EASM) in both the pre-Industrial (PI, 0 ka) and mid-Holocene (MH, 6 ka) simulations. Results show that the PMIP3 model median captures well the large-scale characteristics of the EASM, including the two distinct features of the Meiyu rainbelt and the stepwise meridional displacement of the monsoonal rainbelt. At mid-Holocene, the PMIP3 model median shows significant warming (cooling) during boreal summer (winter) over Eurasia continent that are dominated by the changes of insolation. However, the PMIP3 models fail to simulate a warmer annual mean and winter surface air temperature (TAS) over eastern China as derived from proxy records. The EASM at MH are featured by the changes of large-scale circulation over Eastern China while the changes of precipitation are not significant over its sub-domains of the Southern China and the lower reaches of Yangzi River. The inter-model differences for the monsoon precipitation can be associated with different configurations of the changes in large-scale circulation and the water vapour content, of which the former determines the sign of precipitation changes. The large model spread for the TAS over Tibetan Plateau has a positive relationship with the precipitation in the lower reaches of Yangzi River, yet this relationship does not apply to those PMIP3 models in which the monsoonal precipitation is more sensitive to the changes of large-scale circulation. Except that the PMIP3 model median captured the warming of annual mean TAS over Tibetan Plateau, no significant improvements can be concluded when compared with the PMIP2 models results. KW - cmip5 KW - midholocene KW - monsoon KW - picontrol KW - pmip2 KW - pmip3 AU - Zheng, W AU - Wu, B AU - He, J AU - Yu, Y PY - 2013/02/25/ UR - http://dx.doi.org/10.5194/cp-9-453-2013 DO - doi: 10.5194/cp-9-453-2013 ER - TY - JOUR ID - citeulike:11373903 L3 - citeulike-article-id:11373903 TI - Antarctic temperature changes during the last millennium: evaluation of simulations and reconstructions JF - Quaternary Science Reviews VL - 55 SP - 75 EP - 90 SN - 02773791 N2 - Temperature changes in Antarctica over the last millennium are investigated using proxy records, a set of simulations driven by natural and anthropogenic forcings and one simulation with data assimilation. Over Antarctica, a long term cooling trend in annual mean is simulated during the period 1000–1850. The main contributor to this cooling trend is the volcanic forcing, astronomical forcing playing a dominant role at seasonal timescale. Since 1850, all the models produce an Antarctic warming in response to the increase in greenhouse gas concentrations. We present a composite of Antarctic temperature, calculated by averaging seven temperature records derived from isotope measurements in ice cores. This simple approach is supported by the coherency displayed between model results at these data grid points and Antarctic mean temperature. The composite shows a weak multi-centennial cooling trend during the pre-industrial period and a warming after 1850 that is broadly consistent with model results. In both data and simulations, large regional variations are superimposed on this common signal, at decadal to centennial timescales. The model results appear spatially more consistent than ice core records. We conclude that more records are needed to resolve the complex spatial distribution of Antarctic temperature variations during the last millennium. ► We analyze proxy records and model simulations without and with data assimilation. ► Models display a cooling trend in Antarctica during the period 850–1850 and then a warming. ► The pre-industrial trend is mainly due to the volcanic forcing in annual mean. ► Astronomical forcing plays a dominant role for seasonal trends. ► The model results are in broad agreement with ice core records but are spatially more consistent. KW - antarctica KW - cmip5 KW - model_data_comparison KW - past1000 KW - pmip3 KW - reconstruction AU - Goosse, H AU - Braida, M AU - Crosta, X AU - Mairesse, A AU - Masson-Delmotte, V AU - Mathiot, P AU - Neukom, R AU - Oerter, H AU - Philippon, G AU - Renssen, H AU - Stenni, B AU - van Ommen, T AU - Verleyen, E PY - 2012/11// UR - http://dx.doi.org/10.1016/j.quascirev.2012.09.003 DO - doi: 10.1016/j.quascirev.2012.09.003 ER - TY - JOUR ID - citeulike:13132493 L3 - citeulike-article-id:13132493 TI - Australia’s CMIP5 submission using the CSIRO-Mk3.6 model JF - Australian Meteorological and Oceanographic Journal VL - 63 IS - 1 SP - 1 KW - 1pctco2 KW - abrupt4xco2 KW - cmip5 KW - csiro_model KW - midholocene KW - picontrol KW - pmip3 AU - Jeffrey, S AU - Rotstayn, L AU - Collier, M AU - Dravitzki, S AU - Hamalainen, C AU - Moeseneder, C AU - Wong, K AU - Skytus, J PY - 2013/// ER - TY - JOUR ID - citeulike:12344522 L3 - citeulike-article-id:12344522 TI - Using paleo-climate comparisons to constrain future projections in CMIP5 JF - Climate of the Past Discussions VL - 9 IS - 1 SP - 775 EP - 835 PB - Copernicus Publications N2 - We present a description of the theoretical framework and "best practice" for using the paleo-climate model component of the Coupled Model Intercomparison Project (Phase 5) (CMIP5) to constrain future projections of climate using the same models. The constraints arise from measures of skill in hindcasting paleo-climate changes from the present over 3 periods: the Last Glacial Maximum (LGM) (21 thousand years before present, ka), the mid-Holocene (MH) (6 ka) and the Last Millennium (LM) (850–1850 CE). The skill measures may be used to validate robust patterns of climate change across scenarios or to distinguish between models that have differing outcomes in future scenarios. We find that the multi-model ensemble of paleo-simulations is adequate for addressing at least some of these issues. For example, selected benchmarks for the LGM and MH are correlated to the rank of future projections of precipitation/temperature or sea ice extent to indicate that models that produce the best agreement with paleoclimate information give demonstrably different future results than the rest of the models. We also find that some comparisons, for instance associated with model variability, are strongly dependent on uncertain forcing timeseries, or show time dependent behaviour, making direct inferences for the future problematic. Overall, we demonstrate that there is a strong potential for the paleo-climate simulations to help inform the future projections and urge all the modeling groups to complete this subset of the CMIP5 runs. KW - cmip5 KW - lgm KW - midholocene KW - past1000 KW - pmip3 AU - Schmidt, GA AU - Annan, JD AU - Bartlein, PJ AU - Cook, BI AU - Guilyardi, E AU - Hargreaves, JC AU - Harrison, SP AU - Kageyama, M AU - LeGrande, AN AU - Konecky, B AU - Lovejoy, S AU - Mann, ME AU - Masson-Delmotte, V AU - Risi, C AU - Thompson, D AU - Timmermann, A AU - Tremblay, LB AU - Yiou, P PY - 2013/02/11/ UR - http://dx.doi.org/10.5194/cpd-9-775-2013 DO - doi: 10.5194/cpd-9-775-2013 ER - TY - JOUR ID - citeulike:11415705 L3 - citeulike-article-id:11415705 TI - Mid-Holocene and Last Glacial Maximum climate simulations with the IPSL model—part I: comparing IPSL_CM5A to IPSL_CM4 T2 - Climate Dynamics JF - Climate Dynamics VL - 40 IS - 9-10 SP - 2447 EP - 2468 PB - Springer-Verlag SN - 0930-7575 N2 - The climates of the mid-Holocene (MH), 6,000 years ago, and of the Last Glacial Maximum (LGM), 21,000 years ago, have extensively been simulated, in particular in the framework of the Palaeoclimate Modelling Intercomparion Project. These periods are well documented by paleo-records, which can be used for evaluating model results for climates different from the present one. Here, we present new simulations of the MH and the LGM climates obtained with the IPSL_CM5A model and compare them to our previous results obtained with the IPSL_CM4 model. Compared to IPSL_CM4, IPSL_CM5A includes two new features: the interactive representation of the plant phenology and marine biogeochemistry. But one of the most important differences between these models is the latitudinal resolution and vertical domain of their atmospheric component, which have been improved in IPSL_CM5A and results in a better representation of the mid-latitude jet-streams. The Asian monsoon’s representation is also substantially improved. The global average mean annual temperature simulated for the pre-industrial (PI) period is colder in IPSL_CM5A than in IPSL_CM4 but their climate sensitivity to a CO2 doubling is similar. Here we show that these differences in the simulated PI climate have an impact on the simulated MH and LGM climatic anomalies. The larger cooling response to LGM boundary conditions in IPSL_CM5A appears to be mainly due to differences between the PMIP3 and PMIP2 boundary conditions, as shown by a short wave radiative forcing/feedback analysis based on a simplified perturbation method. It is found that the sensitivity computed from the LGM climate is lower than that computed from 2 × CO2 simulations, confirming previous studies based on different models. For the MH, the Asian monsoon, stronger in the IPSL_CM5A PI simulation, is also more sensitive to the insolation changes. The African monsoon is also further amplified in IPSL_CM5A due to the impact of the interactive phenology. Finally the changes in variability for both models and for MH and LGM are presented taking the example of the El-Niño Southern Oscillation (ENSO), which is very different in the PI simulations. ENSO variability is damped in both model versions at the MH, whereas inconsistent responses are found between the two versions for the LGM. Part 2 of this paper examines whether these differences between IPSL_CM4 and IPSL_CM5A can be distinguished when comparing those results to palaeo-climatic reconstructions and investigates new approaches for model-data comparisons made possible by the inclusion of new components in IPSL_CM5A. KW - cmip5 KW - ipsl_model KW - lgm KW - midholocene KW - picontrol KW - pmip3 AU - Kageyama, Masa AU - Braconnot, Pascale AU - Bopp, Laurent AU - Caubel, Arnaud AU - Foujols, Marie-Alice AU - Guilyardi, Eric AU - Khodri, Myriam AU - Lloyd, James AU - Lombard, Fabien AU - Mariotti, Véronique AU - Marti, Olivier AU - Roy, Tilla AU - Woillez, Marie-Noëlle PY - 2013/09/29/ UR - http://dx.doi.org/10.1007/s00382-012-1488-8 DO - doi: 10.1007/s00382-012-1488-8 ER - TY - JOUR ID - citeulike:11521779 L3 - citeulike-article-id:11521779 TI - Mid-Holocene and last glacial maximum climate simulations with the IPSL model: part II: model-data comparisons T2 - Climate Dynamics JF - Climate Dynamics VL - 40 IS - 9-10 SP - 2469 EP - 2495 PB - Springer-Verlag SN - 0930-7575 N2 - The climates of the mid-Holocene (MH, 6,000 years ago) and the Last Glacial Maximum (LGM, 21,000 years ago) have been extensively documented and as such, have become targets for the evaluation of climate models for climate contexts very different from the present. In Part 1 of the present work, we have studied the MH and LGM simulations performed with the last two versions of the IPSL model: IPSL_CM4, run for the PMIP2/CMIP3 (Coupled Model Intercomparion Project) projects and IPSL_CM5A, run for the most recent PMIP3/CMIP5 projets. We have shown that not only are these models different in their simulations of the PI climate, but also in their simulations of the climatic anomalies for the MH and LGM. In the Part 2 of this paper, we first examine whether palaeo-data can help discriminate between the model performances. This is indeed the case for the African monsoon for the MH or for North America south of the Laurentide ice sheet, the South Atlantic or the southern Indian ocean for the LGM. For the LGM, off-line vegetation modelling appears to offer good opportunities to distinguish climate model results because glacial vegetation proves to be very sensitive to even small differences in LGM climate. For other cases such as the LGM North Atlantic or the LGM equatorial Pacific, the large uncertainty on the SST reconstructions, prevents model discrimination. We have examined the use of other proxy-data for model evaluation, which has become possible with the inclusion of the biogeochemistry morel PISCES in the IPSL_CM5A model. We show a broad agreement of the LGM–PI export production changes with reconstructions. These changes are related to the mixed layer depth in most regions and to sea-ice variations in the high latitudes. We have also modelled foraminifer abundances with the FORAMCLIM model and shown that the changes in foraminifer abundance in the equatorial Pacific are mainly forced by changes in SSTs, hence confirming the SST-foraminifer abundance relationship. Yet, this is not the case in all regions in the North Atlantic, where food availability can have a strong impact of foraminifer abundances. Further work will be needed to exhaustively examine the role of factors other than climate in piloting changes in palaeo-indicators. KW - cmip5 KW - ipsl_model KW - lgm KW - midholocene KW - model_data_comparison KW - picontrol KW - pmip3 AU - Kageyama, Masa AU - Braconnot, Pascale AU - Bopp, Laurent AU - Mariotti, Véronique AU - Roy, Tilla AU - Woillez, Marie-Noëlle AU - Caubel, Arnaud AU - Foujols, Marie-Alice AU - Guilyardi, Eric AU - Khodri, Myriam AU - Lloyd, James AU - Lombard, Fabien AU - Marti, Olivier PY - 2013/10/18/ UR - http://dx.doi.org/10.1007/s00382-012-1499-5 DO - doi: 10.1007/s00382-012-1499-5 ER - TY - JOUR ID - citeulike:12941998 L3 - citeulike-article-id:12941998 TI - The effect of sea level on glacial Indo-Pacific climate JF - Nature Geoscience VL - 6 IS - 6 SP - 485 EP - 491 SN - 1752-0894 KW - cmip5 KW - lgm KW - pmip2 KW - pmip3 KW - reconstruction AU - DiNezio, Pedro AU - Tierney, Jessica PY - 2013/05/19/ UR - http://dx.doi.org/10.1038/ngeo1823 DO - doi: 10.1038/ngeo1823 ER - TY - JOUR ID - citeulike:10541984 L3 - citeulike-article-id:10541984 TI - Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation JF - Nature VL - 484 IS - 7392 SP - 49 EP - 54 PB - Nature Publishing Group SN - 0028-0836 KW - lgm KW - pmip3 AU - Shakun, Jeremy AU - Clark, Peter AU - He, Feng AU - Marcott, Shaun AU - Mix, Alan AU - Liu, Zhengyu AU - Otto-Bliesner, Bette AU - Schmittner, Andreas AU - Bard, Edouard PY - 2012/04/04/ UR - http://dx.doi.org/10.1038/nature10915 DO - doi: 10.1038/nature10915 ER - TY - JOUR ID - citeulike:10074579 L3 - citeulike-article-id:10074579 TI - Climate Sensitivity Estimated from Temperature Reconstructions of the Last Glacial Maximum JF - Science VL - 334 IS - 6061 SP - 1385 EP - 1388 PB - American Association for the Advancement of Science SN - 1095-9203 N2 - Assessing the impact of future anthropogenic carbon emissions is currently impeded by uncertainties in our knowledge of equilibrium climate sensitivity to atmospheric carbon dioxide doubling. Previous studies suggest 3 kelvin (K) as the best estimate, 2 to 4.5 K as the 66% probability range, and nonzero probabilities for much higher values, the latter implying a small chance of high-impact climate changes that would be difficult to avoid. Here, combining extensive sea and land surface temperature reconstructions from the Last Glacial Maximum with climate model simulations, we estimate a lower median (2.3 K) and reduced uncertainty (1.7 to 2.6 K as the 66% probability range, which can be widened using alternate assumptions or data subsets). Assuming that paleoclimatic constraints apply to the future, as predicted by our model, these results imply a lower probability of imminent extreme climatic change than previously thought. KW - lgm KW - pmip3 AU - Schmittner, Andreas AU - Urban, Nathan AU - Shakun, Jeremy AU - Mahowald, Natalie AU - Clark, Peter AU - Bartlein, Patrick AU - Mix, Alan AU - Rosell-Melé, Antoni PY - 2011/12/09/ UR - http://dx.doi.org/10.1126/science.1203513 DO - doi: 10.1126/science.1203513 ER - TY - JOUR ID - citeulike:7964560 L3 - citeulike-article-id:7964560 TI - Pollen-based continental climate reconstructions at 6 and 21 ka: a global synthesis T2 - Climate Dynamics JF - Climate Dynamics VL - 37 IS - 3-4 SP - 775 EP - 802 PB - Springer-Verlag SN - 0930-7575 N2 - Subfossil pollen and plant macrofossil data derived from 14C-dated sediment profiles can provide quantitative information on glacial and interglacial climates. The data allow climate variables related to growing-season warmth, winter cold, and plant-available moisture to be reconstructed. Continental-scale reconstructions have been made for the mid-Holocene (MH, around 6 ka) and Last Glacial Maximum (LGM, around 21 ka), allowing comparison with palaeoclimate simulations currently being carried out as part of the fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change. The synthesis of the available MH and LGM climate reconstructions and their uncertainties, obtained using modern-analogue, regression and model-inversion techniques, is presented for four temperature variables and two moisture variables. Reconstructions of the same variables based on surface-pollen assemblages are shown to be accurate and unbiased. Reconstructed LGM and MH climate anomaly patterns are coherent, consistent between variables, and robust with respect to the choice of technique. They support a conceptual model of the controls of Late Quaternary climate change whereby the first-order effects of orbital variations and greenhouse forcing on the seasonal cycle of temperature are predictably modified by responses of the atmospheric circulation and surface energy balance. KW - lgm KW - midholocene KW - pmip3 KW - reconstruction AU - Bartlein, PJ AU - Harrison, SP AU - Brewer, S AU - Connor, S AU - Davis, BAS AU - Gajewski, K AU - Guiot, J AU - Harrison-Prentice, TI AU - Henderson, A AU - Peyron, O AU - Prentice, IC AU - Scholze, M AU - Seppä, H AU - Shuman, B AU - Sugita, S AU - Thompson, RS AU - Viau, AE AU - Williams, J AU - Wu, H PY - 2011/08/01/ UR - http://dx.doi.org/10.1007/s00382-010-0904-1 DO - doi: 10.1007/s00382-010-0904-1 ER - TY - JOUR ID - citeulike:12824766 L3 - citeulike-article-id:12824766 TI - Last Glacial Maximum ice sheet impacts on North Atlantic climate variability: The importance of the sea ice lid JF - Geophysical Research Letters VL - 40 IS - 24 SP - 6378 EP - 6383 SN - 00948276 N2 - Last Glacial Maximum (LGM) ICE-5G (VM2), ICE-6G (VM5a), and Paleoclimate Modelling Intercomparison Project Phase 3 ice sheet reconstructions are employed in high-resolution coupled climate model simulations to investigate the changes they induce in North Atlantic climate variability. An initial ICE-5G (VM2) experiment develops a rapid increase of sea ice extent once a thermal threshold is exceeded in this multimillennial simulation. Subpolar sea ice concentration and thickness are found to be strongly impacted by topographically induced downstream thermal effects from the Laurentide Ice Sheet in each of the reconstructions. However, in the two additional LGM perturbation experiments, the modeled changes in sea ice area are sufficiently similar to the LGM ICE-5G (VM2) experiment to lead to an equilibrium Atlantic Meridional Overturning Circulation strength that is also reduced by the same ~40% from preindustrial even though we find significant variation among the models in the deep convection regions of the subpolar glacial North Atlantic. Model-predicted sea ice concentrations in this critical region exceed those based upon multiproxy reconstructions, and we trace these significant differences to the intensity of the interannual variability of sea ice cover predictions. KW - ccm3_model KW - lgm KW - pmip3 AU - Vettoretti, Guido AU - Peltier, Richard PY - 2013/12/28/ UR - http://dx.doi.org/10.1002/2013gl058486 DO - doi: 10.1002/2013gl058486 ER - TY - JOUR ID - citeulike:12811121 L3 - citeulike-article-id:12811121 TI - Examining Internal and External Contributors to Greenland Climate Variability Using CCSM3 JF - J. Climate VL - 26 IS - 24 SP - 9745 EP - 9773 PB - American Meteorological Society N2 - AbstractGreenland climate variability is connected to internal and external sources of global climate forcing in six millennium simulations using Community Climate System Model, version 3. The external forcings employed are consistent with the protocols of Paleoclimate Modelling Intercomparison Project Phase 3. Many simulated internal climate modes are characterized over the years 850?1850, including the Atlantic meridional overturning circulation (AMOC), the Atlantic multidecadal oscillation (AMO), the east Atlantic pattern (EA), the El Niño?Southern Oscillation, the North Atlantic Oscillation (NAO), the North Atlantic sea ice extent, and the Pacific decadal oscillation (PDO). Lagged correlation and multivariate regression methods connect Greenland temperatures and precipitation to these internal modes and external sources of climate variability.Greenland temperature and precipitation are found to relate most strongly to North Atlantic sea ice extent, the AMO, and the AMOC, that are themselves strongly interconnected. Furthermore, approximately half of the multidecadal variability in Greenland temperature and precipitation are captured through linear relationships with volcanic aerosol optical depth, solar insolation (including total solar irradiance and local orbital variability), the NAO, the EA, and the PDO. Relationships are robust with volcanic aerosol optical depth, solar insolation, and an index related to latitudinal shifts of the North Atlantic jet. Differences attributable to model resolution are also identified in the results, such as lower variability in the AMOC and Greenland temperature in the higher-resolution simulations. Finally, a regression model is applied to simulations of the industrial period to show that natural sources alone only explain the variability in simulated Greenland temperature and precipitation up to the 1950s and 1970s, respectively. KW - ccm3_model KW - past1000 KW - pmip3 AU - Andres, Heather AU - Peltier, WR PY - 2013/08/21/ UR - http://dx.doi.org/10.1175/jcli-d-12-00845.1 DO - doi: 10.1175/jcli-d-12-00845.1 ER - TY - JOUR ID - citeulike:12155462 L3 - citeulike-article-id:12155462 TI - Consistent large-scale temperature responses in warm and cold climates JF - Geophys. Res. Lett. VL - 40 IS - 9 SP - 1817 EP - 1823 SN - 00948276 N2 - Climate-model simulations of the large-scale temperature responses to increased radiative forcing include enhanced land-sea contrast, stronger response at higher latitudes than in the tropics, and differential responses in warm and cool season climates to uniform forcing. Here we show that these patterns are also characteristic of model simulations of past climates. The differences in the responses over land as opposed to over the ocean, between high and low latitudes, and between summer and winter are remarkably consistent (proportional and nearly linear) across simulations of both cold and warm climates. Similar patterns also appear in historical observations and paleoclimatic reconstructions, implying that such responses are characteristic features of the climate system and not simple model artifacts, thereby increasing our confidence in the ability of climate models to correctly simulate different climatic states. KW - 1pctco2 KW - abrupt4xco2 KW - cmip5 KW - historical KW - lgm KW - midholocene KW - model_data_comparison KW - picontrol KW - pmip3 AU - Izumi, Kenji AU - Bartlein, Patrick AU - Harrison, Sandy PY - 2013/05/16/ UR - http://dx.doi.org/10.1002/grl.50350 DO - doi: 10.1002/grl.50350 ER - TY - JOUR ID - citeulike:12480064 L3 - citeulike-article-id:12480064 TI - Precipitation scaling with temperature in warm and cold climates: An analysis of CMIP5 simulations JF - Geophysical Research Letters VL - 40 IS - 15 SP - 4018 EP - 4024 SN - 00948276 N2 - We investigate the scaling between precipitation and temperature changes in warm and cold climates using six models that have simulated the response to both increased CO2 and Last Glacial Maximum (LGM) boundary conditions. Globally, precipitation increases in warm and decreases in cold climates by between 1.5 to 3%/°C. Precipitation sensitivity to temperature changes are lower over land than ocean and lower over tropical land compared to extratropical land, reflecting the constraint of water availability. The wet tropics get wetter in warm and drier in cold climates, but the changes in dry areas differ among models. Seasonal changes of tropical precipitation in a warmer world also reflect this “rich get richer” syndrome. Precipitation seasonality is decreased in the cold-climate state. The simulated changes in precipitation per degree temperature change are comparable to the observed changes in both the historical period and the LGM. KW - 1pctco2 KW - abrupt4xco2 KW - cmip5 KW - historical KW - lgm KW - midholocene KW - model_data_comparison KW - picontrol KW - pmip3 AU - Li, Guangqi AU - Harrison, Sandy AU - Bartlein, Patrick AU - Izumi, Kenji AU - Colin Prentice, I PY - 2013/08/16/ UR - http://dx.doi.org/10.1002/grl.50730 DO - doi: 10.1002/grl.50730 ER - TY - JOUR ID - citeulike:12941155 L3 - citeulike-article-id:12941155 TI - Climate model benchmarking with glacial and mid-Holocene climates T2 - Climate Dynamics JF - Climate Dynamics VL - 43 IS - 3-4 SP - 671 EP - 688 PB - Springer Berlin Heidelberg N2 - Past climates provide a test of models’ ability to predict climate change. We present a comprehensive evaluation of state-of-the-art models against Last Glacial Maximum and mid-Holocene climates, using reconstructions of land and ocean climates and simulations from the Palaeoclimate Modelling and Coupled Modelling Intercomparison Projects. Newer models do not perform better than earlier versions despite higher resolution and complexity. Differences in climate sensitivity only weakly account for differences in model performance. In the glacial, models consistently underestimate land cooling (especially in winter) and overestimate ocean surface cooling (especially in the tropics). In the mid-Holocene, models generally underestimate the precipitation increase in the northern monsoon regions, and overestimate summer warming in central Eurasia. Models generally capture large-scale gradients of climate change but have more limited ability to reproduce spatial patterns. Despite these common biases, some models perform better than others. KW - cmip5 KW - lgm KW - midholocene KW - model_data_comparison KW - picontrol KW - pmip2 KW - pmip3 AU - Harrison, SP AU - Bartlein, PJ AU - Brewer, S AU - Prentice, IC AU - Boyd, M AU - Hessler, I AU - Holmgren, K AU - Izumi, K AU - Willis, K PY - 2014/// UR - http://dx.doi.org/10.1007/s00382-013-1922-6 DO - doi: 10.1007/s00382-013-1922-6 ER -