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--- pmip3:wg:p2f:paperseval [2017/02/13 14:21]
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+++ pmip3:wg:p2f:paperseval [2017/02/13 16:55]
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  ~~DISCUSSION~~
-====== Overview of papers ======
+====== Some papers with a focus on evaluating PMIP models ======
 Chronological by publication date, most recent first:
-New additions - details to be added...
 ==== The University of Victoria Cloud Feedback Emulator (UVic-CFE): cloud radiative feedbacks in an intermediate complexity model ====
 In review at GMD, doi:10.5194/gmd-2016-220
+http://www.geosci-model-dev-discuss.net/gmd-2016-220/ (open access)
-http://www.geosci-model-dev-discuss.net/gmd-2016-220/
+from the abstract: ''Here, we describe and evaluate a method for applying GCM-derived shortwave and longwave cloud feedbacks from 4xCO2 and Last Glacial Maximum experiments to the University of Victoria Earth System Climate Model. The method generally captures the spread in top-of-the-atmosphere radiative feedbacks between the original GCMs, which impacts the magnitude and spatial distribution of surface temperature changes and climate sensitivity. These results suggest that the method is suitable to incorporate multi-model cloud feedback uncertainties in ensemble simulations with a single intermediate complexity model.''
-from the abstract: “Here, we describe and evaluate a method for applying GCM-derived shortwave and longwave cloud feedbacks from 4xCO2 and Last Glacial Maximum experiments to the University of Victoria Earth System Climate Model. The method generally captures the spread in top-of-the-atmosphere radiative feedbacks between the original GCMs, which impacts the magnitude and spatial distribution of surface temperature changes and climate sensitivity. These results suggest that the method is suitable to incorporate multi-model cloud feedback uncertainties in ensemble simulations with a single intermediate complexity model.”
 ==== Nonlinear climate sensitivity and its implications for future greenhouse warming ====
-Tobias Friedrich, Axel Timmermann, Michelle Tigchelaar, Oliver Elison Timm and Andrey Ganopolski
+Tobias Friedrich, Axel Timmermann, Michelle Tigchelaar, Oliver Elison Timm and Andrey Ganopolski, Science Advances  09 Nov 2016, Vol. 2, no. 11, e1501923, DOI: 10.1126/sciadv.1501923 http://advances.sciencemag.org/content/2/11/e1501923.full
-Science Advances  09 Nov 2016, Vol. 2, no. 11, e1501923, DOI: 10.1126/sciadv.1501923
-http://advances.sciencemag.org/content/2/11/e1501923.full
-abstract: Global mean surface temperatures are rising in response to anthropogenic greenhouse gas emissions. The magnitude of this warming at equilibrium for a given radiative forcing—referred to as specific equilibrium climate sensitivity (S)—is still subject to uncertainties. We estimate global mean temperature variations and S using a 784,000-year-long field reconstruction of sea surface temperatures and a transient paleoclimate model simulation. Our results reveal that S is strongly dependent on the climate background state, with significantly larger values attained during warm phases. Using the Representative Concentration Pathway 8.5 for future greenhouse radiative forcing, we find that the range of paleo-based estimates of Earth’s future warming by 2100 CE overlaps with the upper range of climate simulations conducted as part of the Coupled Model Intercomparison Project Phase 5 (CMIP5). Furthermore, we find that within the 21st century, global mean temperatures will very likely exceed maximum levels reconstructed for the last 784,000 years. On the basis of temperature data from eight glacial cycles, our results provide an independent validation of the magnitude of current CMIP5 warming projections.
+abstract: ''Global mean surface temperatures are rising in response to anthropogenic greenhouse gas emissions. The magnitude of this warming at equilibrium for a given radiative forcing—referred to as specific equilibrium climate sensitivity (S)—is still subject to uncertainties. We estimate global mean temperature variations and S using a 784,000-year-long field reconstruction of sea surface temperatures and a transient paleoclimate model simulation. Our results reveal that S is strongly dependent on the climate background state, with significantly larger values attained during warm phases. Using the Representative Concentration Pathway 8.5 for future greenhouse radiative forcing, we find that the range of paleo-based estimates of Earth’s future warming by 2100 CE overlaps with the upper range of climate simulations conducted as part of the Coupled Model Intercomparison Project Phase 5 (CMIP5). Furthermore, we find that within the 21st century, global mean temperatures will very likely exceed maximum levels reconstructed for the last 784,000 years. On the basis of temperature data from eight glacial cycles, our results provide an independent validation of the magnitude of current CMIP5 warming projections.''
 ==== Could the Pliocene constrain the equilibrium climate sensitivity? ====
-J. C. Hargreaves and J. D. Annan
+J. C. Hargreaves and J. D. Annan, Clim. Past, 12, 1591-1599, 2016
-Clim. Past, 12, 1591-1599, 2016
+doi:10.5194/cp-12-1591-2016, http://www.clim-past.net/12/1591/2016/ (open access)
-doi:10.5194/cp-12-1591-2016
-http://www.clim-past.net/12/1591/2016/
-Short summary “The mid-Pliocene Warm Period, 3 million years ago, was the most recent interval with high greenhouse gases. By modelling the period with the same models used for future projections, we can link the past and future climates. Here we use data from the mid-Pliocene to produce a tentative result for equilibrium climate sensitivity. We show that there are considerable uncertainties that strongly influence the result, but we are optimistic that these may be reduced in the next few years.”
-==== Terrestrial biosphere changes over the last 120 kyr and their
+Short summary ''The mid-Pliocene Warm Period, 3 million years ago, was the most recent interval with high greenhouse gases. By modelling the period with the same models used for future projections, we can link the past and future climates. Here we use data from the mid-Pliocene to produce a tentative result for equilibrium climate sensitivity. We show that there are considerable uncertainties that strongly influence the result, but we are optimistic that these may be reduced in the next few years.''
-impact on ocean δ 13C. ====
+==== Terrestrial biosphere changes over the last 120 kyr. ====
 Hoogakker BAA, Smith RS, Singarayer JS, Marchant R, Prentice IC, Allen
 J, Anderson RS, Bhagwat SA, Behling H, Borisova O, and Bush M, et al.
-(2015).  Climate of Past Discussions, 11, pp. 1031-1091
+(2015). Clim. Past, 12, 51-73, 2016, doi:10.5194/cp-12-51-2016
+http://www.clim-past.net/12/51/2016/cp-12-51-2016.html (open access)
-From the conclusions, “We have used a new global synthesis and biomization of long pollen records in conjunction with model simulations to analyse the sensitivity of the global terrestrial biosphere to climate change over the last glacial–interglacial cycle. Model output and biomized pollen data generally agree, lending confidence to our global-scale analysis of the carbon cycle derived from the model simulations. We used the models to estimate changes in global terrestrial net primary production and carbon storage. Carbon storage variations have a strong 23kyr (precessional) cycle in the first half of the glacial cycle in particular. “
+From the conclusions, ''We have used a new global synthesis and biomization of long pollen records in conjunction with model simulations to analyse the sensitivity of the global terrestrial biosphere to climate change over the last glacial–interglacial cycle. Model output and biomized pollen data generally agree, lending confidence to our global-scale analysis of the carbon cycle derived from the model simulations. We used the models to estimate changes in global terrestrial net primary production and carbon storage. Carbon storage variations have a strong 23kyr (precessional) cycle in the first half of the glacial cycle in particular. ''
 ==== Evaluation of CMIP5 palaeo-simulations to improve climate projections.  ====
@@ Line 44: / Line 38: @@
 http://www.nature.com/nclimate/journal/v5/n8/full/nclimate2649.html
-from abstract: “Past climate changes provide a unique opportunity for out-of-sample evaluation of model performance. Palaeo-evaluation has shown that the large-scale changes seen in twenty-first-century projections, including enhanced land–sea temperature contrast, latitudinal amplification, changes in temperature seasonality and scaling of precipitation with temperature, are likely to be realistic. Although models generally simulate changes in large-scale circulation sufficiently well to shift regional climates in the right direction, they often do not predict the correct magnitude of these changes. Differences in performance are only weakly related to modern-day biases or climate sensitivity, and more sophisticated models” [within the CMIP model ensembles] “ are not better at simulating climate changes. Although models correctly capture the broad patterns of climate change, improvements are required to produce reliable regional projections.”
+from abstract: ''Past climate changes provide a unique opportunity for out-of-sample evaluation of model performance. Palaeo-evaluation has shown that the large-scale changes seen in twenty-first-century projections, including enhanced land–sea temperature contrast, latitudinal amplification, changes in temperature seasonality and scaling of precipitation with temperature, are likely to be realistic. Although models generally simulate changes in large-scale circulation sufficiently well to shift regional climates in the right direction, they often do not predict the correct magnitude of these changes. Differences in performance are only weakly related to modern-day biases or climate sensitivity, and more sophisticated models'' [within the CMIP model ensembles] ''are not better at simulating climate changes. Although models correctly capture the broad patterns of climate change, improvements are required to produce reliable regional projections.''
-==== Glacial Atlantic overturning increased by wind stress in climate models==== 2015
+==== Glacial Atlantic overturning increased by wind stress in climate models ====
-Juan Muglia and Andreas Schmittner
+Juan Muglia and Andreas Schmittner, 2015,  Geophys. Res. Lett., 42, doi:10.1002/2015GL064583, http://people.oregonstate.edu/~schmita2/pdf/M/muglia15grl.pdf
-Geophys. Res. Lett., 42, doi:10.1002/2015GL064583
-http://people.oregonstate.edu/~schmita2/pdf/M/muglia15grl.pdf
-excerpts from conclusions: “Since LGM wind stress, closure of Bering Strait [Hu et al., 2010], and increased tidal mixing [Schmittner et al., 2015] all tend to increase the strength and depth of the AMOC, a countering effect has to be invoked to reproduce observations of a weaker and shallower overturning during the LGM.” … “It will be an important task for future work to resolve the apparent inconsistency between PMIP models’ LGM circulation and reconstructions.This inconsistency casts doubt on future AMOC projections with these models [e.g., Weaver et al., 2012]. One possible explanation may be that not all PMIP3 models were in equilibrium [Zhang et al., 2013].”
+excerpts from conclusions: ''Since LGM wind stress, closure of Bering Strait [Hu et al., 2010], and increased tidal mixing [Schmittner et al., 2015] all tend to increase the strength and depth of the AMOC, a countering effect has to be invoked to reproduce observations of a weaker and shallower overturning during the LGM.” … “It will be an important task for future work to resolve the apparent inconsistency between PMIP models’ LGM circulation and reconstructions.This inconsistency casts doubt on future AMOC projections with these models [e.g., Weaver et al., 2012]. One possible explanation may be that not all PMIP3 models were in equilibrium [Zhang et al., 2013].''
-Yin Q.Z. and Berger A., 2015. Interglacial analogues of the Holocene and its natural near future. Quaternary Science Reviews, 120, 28-46.
+==== Interglacial analogues of the Holocene and its natural near future. ====
-http://www.sciencedirect.com/science/article/pii/S027737911500150X
+Yin Q.Z. and Berger A., 2015.  Quaternary Science Reviews, 120, 28-46, http://www.sciencedirect.com/science/article/pii/S027737911500150X
 Highlights:
-“•Five warm interglacials are intercompared with both snapshot and transient simulations.
+''•Five warm interglacials are intercompared with both snapshot and transient simulations.
 •Relationships between astronomical parameters and temperature and precipitation of different latitudes are examined.
 •Contributions of insolation and CO2 to the intensity and duration of the five interglacials are discussed.
-•Analogue of the Holocene and its natural future is looked for from the past interglacials.”
+•Analogue of the Holocene and its natural future is looked for from the past interglacials.''
 ==== Energy-balance mechanisms underlying consistent large-scale temperature responses in warm and cold climates. ====
-Izumi, K., Bartlein, P.J. and Harrison, S.P., 2015.  Climate Dynamics 44: 3111 DOI 10.1007/s00382-014-2189-2.
+Izumi, K., Bartlein, P.J. and Harrison, S.P., 2015.  Climate Dynamics 44: 3111 DOI 10.1007/s00382-014-2189-2, http://link.springer.com/article/10.1007/s00382-014-2189-2 (open access)
-open access
-http://link.springer.com/article/10.1007/s00382-014-2189-2
-“Climate simulations show consistent large-scale temperature responses including amplified land–ocean contrast, high-latitude/low-latitude contrast, and changes in seasonality in response to year-round forcing, in both warm and cold climates, and these responses are proportional and nearly linear across multiple climate states. We examine the possibility that a small set of common mechanisms controls these large-scale responses using a simple energy-balance model to decompose the temperature changes shown in multiple lgm and abrupt4 × CO2 simulations from the CMIP5 archive. Changes in the individual components of the energy balance are broadly consistent across the models. Although several components are involved in the overall temperature responses, surface downward clear-sky longwave radiation is the most important component driving land–ocean contrast and high-latitude amplification in both warm and cold climates. Surface albedo also plays a significant role in promoting high-latitude amplification in both climates and in intensifying the land–ocean contrast in the warm climate case. The change in seasonality is a consequence of the changes in land–ocean and high-latitude/low-latitude contrasts rather than an independent temperature response. This is borne out by the fact that no single component stands out as being the major cause of the change in seasonality, and the relative importance of individual components is different in cold and warm climates.”
+''Climate simulations show consistent large-scale temperature responses including amplified land–ocean contrast, high-latitude/low-latitude contrast, and changes in seasonality in response to year-round forcing, in both warm and cold climates, and these responses are proportional and nearly linear across multiple climate states. We examine the possibility that a small set of common mechanisms controls these large-scale responses using a simple energy-balance model to decompose the temperature changes shown in multiple lgm and abrupt4 × CO2 simulations from the CMIP5 archive. Changes in the individual components of the energy balance are broadly consistent across the models. Although several components are involved in the overall temperature responses, surface downward clear-sky longwave radiation is the most important component driving land–ocean contrast and high-latitude amplification in both warm and cold climates. Surface albedo also plays a significant role in promoting high-latitude amplification in both climates and in intensifying the land–ocean contrast in the warm climate case. The change in seasonality is a consequence of the changes in land–ocean and high-latitude/low-latitude contrasts rather than an independent temperature response. This is borne out by the fact that no single component stands out as being the major cause of the change in seasonality, and the relative importance of individual components is different in cold and warm climates.''
 ==== On the state dependency of fast feedback processes in (paleo) climate sensitivity ====
 A. S. von der Heydt, P. Köhler, R. S. W. van de Wal, H. A. Dijkstra
-GRL, Volume 41, Issue 18, pages 6484–6492, 28 September 2014, DOI: 10.1002/2014GL061121
+GRL, Volume 41, Issue 18, pages 6484–6492, 28 September 2014, DOI: 10.1002/2014GL061121, http://onlinelibrary.wiley.com/doi/10.1002/2014GL061121/abstract
-http://onlinelibrary.wiley.com/doi/10.1002/2014GL061121/abstract
-from abstract “Here we assess the dependency of the fast feedback processes on the background climate state using data of the last 800 kyr and a box model of the climate system for interpretation. Applying a new method to account for background state dependency, we find Sa=0.61±0.07 K (W m−2)−1(±1σ) using a reconstruction of Last Glacial Maximum (LGM) cooling of −4.0 K and significantly lower climate sensitivity during glacial climates. Due to uncertainties in reconstructing the LGM temperature anomaly, Sa is estimated in the range Sa = 0.54–0.95 K (W m−2)−1.”
+from abstract ''Here we assess the dependency of the fast feedback processes on the background climate state using data of the last 800 kyr and a box model of the climate system for interpretation. Applying a new method to account for background state dependency, we find Sa=0.61±0.07 K (W m−2)−1(±1σ) using a reconstruction of Last Glacial Maximum (LGM) cooling of −4.0 K and significantly lower climate sensitivity during glacial climates. Due to uncertainties in reconstructing the LGM temperature anomaly, Sa is estimated in the range Sa = 0.54–0.95 K (W m−2)−1.''
 ==== Model benchmarking with glacial and mid-Holocene climates. ====
-Harrison, S.P., Bartlein, P.J., Brewer, S., Prentice, I.C., Boyd, M., Hessler, I., Holmgren, K., Izumi, K., and Willis, K., 2013.  Climate Dynamics 43: 671-688. DOI 1007/s00382-013-1922-6
+Harrison, S.P., Bartlein, P.J., Brewer, S., Prentice, I.C., Boyd, M., Hessler, I., Holmgren, K., Izumi, K., and Willis, K., 2013.  Climate Dynamics 43: 671-688. DOI 1007/s00382-013-1922-6, http://link.springer.com/article/10.1007%2Fs00382-013-1922-6
-http://link.springer.com/article/10.1007%2Fs00382-013-1922-6
-“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. 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.”
+''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. 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.''
 ==== Consistent large-scale temperature responses in warm and cold climates. ====
-Izumi, K., Bartlein, P.J. and Harrison, S.P., 2013. , Geophysical Research Letters 40: 1817-1823, doi:10.1002/grl.50350.
+Izumi, K., Bartlein, P.J. and Harrison, S.P., 2013. , Geophysical Research Letters 40: 1817-1823, doi:10.1002/grl.50350, http://onlinelibrary.wiley.com/doi/10.1002/grl.50350/full
-http://onlinelibrary.wiley.com/doi/10.1002/grl.50350/full
 Abstract:
-“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.”
+''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.''
 ==== Making sense of palaeoclimate sensitivity ====
 PALAEOSENS Project Members
-Nature 491, 683–691 (29 November 2012) doi:10.1038/nature11574
+Nature 491, 683–691 (29 November 2012) doi:10.1038/nature11574, http://www.nature.com/nature/journal/v491/n7426/abs/nature11574.html
-http://www.nature.com/nature/journal/v491/n7426/abs/nature11574.html
-from abstract “…to improve intercomparison of palaeoclimate sensitivity estimates in a manner compatible with equilibrium projections for future climate change. Over the past 65 million years, this reveals a climate sensitivity (in K W−1 m2) of 0.3–1.9 or 0.6–1.3 at 95% or 68% probability, respectively. The latter implies a warming of 2.2–4.8 K per doubling of atmospheric CO2, which agrees with IPCC estimates.”
+from abstract: ''…to improve intercomparison of palaeoclimate sensitivity estimates in a manner compatible with equilibrium projections for future climate change. Over the past 65 million years, this reveals a climate sensitivity (in K W−1 m2) of 0.3–1.9 or 0.6–1.3 at 95% or 68% probability, respectively. The latter implies a warming of 2.2–4.8 K per doubling of atmospheric CO2, which agrees with IPCC estimates.''

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