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 - Geophysical Research Letters VL - 40 IS - 5 SP - 965 EP - 970 SN - 00948276 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 - n/a EP - n/a 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 SP - 1 EP - 14 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 - 2013/// 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 - Abstract Reconstructions 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, a division of Macmillan Publishers Limited. All Rights Reserved. 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 - 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 - Abstract Greenland 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 - 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 - Geophysical Research Letters 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 SP - 1 EP - 18 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 - 2013/// UR - http://dx.doi.org/10.1007/s00382-013-1922-6 DO - doi: 10.1007/s00382-013-1922-6 ER -