The PMIP4 Last Glacial Maximum experiments: Preliminary results and comparison with the PMIP3 simulations
Université Paris-Saclay1, University of Reading2, Max Planck Society3, University of Arizona4, Yale University5, University of Tokyo6, University of Toronto7, University of Leeds8, University of Bristol9, Goddard Institute for Space Studies10, Russian Academy of Sciences11, Japan Agency for Marine-Earth Science and Technology12, University of Bremen13, VU University Amsterdam14, National Center for Atmospheric Research15
TL;DR: In this article, a new generation of climate models has been used to generate LGM simulations as part of the PMIP contribution to the Coupled model intercomparison project (CMIP).
Abstract: The Last Glacial Maximum (LGM, ∼ 21 000 years ago) has been a major focus for evaluating how well state-of-the-art climate models simulate climate changes as large as those expected in the future using paleoclimate reconstructions. A new generation of climate models has been used to generate LGM simulations as part of the Paleoclimate Modelling Intercomparison Project (PMIP) contribution to the Coupled Model Intercomparison Project (CMIP). Here, we provide a preliminary analysis and evaluation of the results of these LGM experiments (PMIP4, most of which are PMIP4-CMIP6) and compare them with the previous generation of simulations (PMIP3, most of which are PMIP3-CMIP5). We show that the global averages of the PMIP4 simulations span a larger range in terms of mean annual surface air temperature and mean annual precipitation compared to the PMIP3-CMIP5 simulations, with some PMIP4 simulations reaching a globally colder and drier state. However, the multi-model global cooling average is similar for the PMIP4 and PMIP3 ensembles, while the multi-model PMIP4 mean annual precipitation average is drier than the PMIP3 one. There are important differences in both atmospheric and oceanic circulations between the two sets of experiments, with the northern and southern jet streams being more poleward and the changes in the Atlantic Meridional Overturning Circulation being less pronounced in the PMIP4-CMIP6 simulations than in the PMIP3-CMIP5 simulations. Changes in simulated precipitation patterns are influenced by both temperature and circulation changes. Differences in simulated climate between individual models remain large. Therefore, although there are differences in the average behaviour across the two ensembles, the new simulation results are not fundamentally different from the PMIP3-CMIP5 results. Evaluation of large-scale climate features, such as land–sea contrast and polar amplification, confirms that the models capture these well and within the uncertainty of the paleoclimate reconstructions. Nevertheless, regional climate changes are less well simulated: the models underestimate extratropical cooling, particularly in winter, and precipitation changes. These results point to the utility of using paleoclimate simulations to understand the mechanisms of climate change and evaluate model performance.
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TL;DR: In this paper, a proxy-constrained, full-field reanalysis of surface temperature change spanning the Last Glacial Maximum to present at 200-year resolution is presented.
Abstract: Climate changes across the past 24,000 years provide key insights into Earth system responses to external forcing Climate model simulations1,2 and proxy data3–8 have independently allowed for study of this crucial interval; however, they have at times yielded disparate conclusions Here, we leverage both types of information using paleoclimate data assimilation9,10 to produce the first proxy-constrained, full-field reanalysis of surface temperature change spanning the Last Glacial Maximum to present at 200-year resolution We demonstrate that temperature variability across the past 24 thousand years was linked to two primary climatic mechanisms: radiative forcing from ice sheets and greenhouse gases; and a superposition of changes in the ocean overturning circulation and seasonal insolation In contrast with previous proxy-based reconstructions6,7 our results show that global mean temperature has slightly but steadily warmed, by ~05 °C, since the early Holocene (around 9 thousand years ago) When compared with recent temperature changes11, our reanalysis indicates that both the rate and magnitude of modern warming are unusual relative to the changes of the past 24 thousand years Paleoclimate datasets are integrated with a climate model to reconstruct global surface temperature since the Last Glacial Maximum, showing sustained warming until the mid-Holocene
142 citations
01 Dec 2012
TL;DR: This paper showed that robust subtropical precipitation declines have been a prominent feature of general circulation model (GCM) responses to future greenhouse warming, and extended this work to 36 new CMIP5 models, and found that these robust precipitation declines are also found mainly between sub- tropical minima and midlatitude precipitation maxima, implicating dynamic poleward expansion of dry zones rather than thermodynamic amplification of dry-wet contrasts.
Abstract: [1] Robust subtropical precipitation declines have been a prominent feature of general circulation model (GCM) responses to future greenhouse warming. Recent work by the authors showed that for the models making up the Coupled Model Intercomparison Project phase 3 (CMIP3), this drying was found mainly in the midlatitude-driven precipitation poleward of the model subtropical precipitation minima. Here, using more comprehensive diagnostics, we extend that work to 36 new CMIP5 models, and find that CMIP5 robust precipitation declines are also found mainly between subtropical minima and midlatitude precipitation maxima, implicating dynamic poleward expansion of dry zones rather than thermodynamic amplification of dry-wet contrasts. We also give the full seasonal cycle of these projected declines, showing that they are much more widespread in local spring than in local fall, and that for most of the year in the Northern Hemisphere they are entirely confined to the Atlantic side of the globe.
137 citations
TL;DR: In this article , the authors presented a new reconstruction of surface air temperature and sea surface temperature for the Last Glacial Maximum using the full range of general circulation model (GCM) simulations which contributed to three generations of the PMIP database, and an improved methodology based on an ensemble Kalman filter.
Abstract: Abstract. We present a new reconstruction of surface air temperature and sea surface temperature for the Last Glacial Maximum. The method blends model fields and sparse proxy-based point estimates through a data assimilation approach. Our reconstruction updates that of Annan and Hargreaves (2013), using the full range of general circulation model (GCM) simulations which contributed to three generations of the PMIP database, three major compilations of gridded sea surface temperature (SST) and surface air temperature (SAT) estimates from proxy data, and an improved methodology based on an ensemble Kalman filter. Our reconstruction has a global annual mean surface air temperature anomaly of -4.5±0.9 ∘C relative to the pre-industrial climate. This is slightly colder than the previous estimate of Annan and Hargreaves (2013), with an upwards revision on the uncertainty due to different methodological assumptions. It is, however, substantially less cold than the recent reconstruction of Tierney et al. (2020). We show that the main reason for this discrepancy is in the choice of prior. We recommend the use of the multi-model ensemble of opportunity as potentially offering a credible prior, but it is important that the range of models included in the PMIP ensembles represent the main sources of uncertainty as realistically and comprehensively as practicable if they are to be used in this way.
20 citations
TL;DR: In this paper, the authors used an updated synthesis of coral and bivalve monthly resolved records to build composite records of seasonality and interannual variability in four regions of the tropical Pacific: Eastern Pacific (EP), Central Pacific (CP), Western Pacific (WP) and South West Pacific (SWP).
18 citations
TL;DR: In this article, the authors investigate the impact of a range of surface conditions in the Southern Ocean in the iLOVECLIM model using nine simulations obtained with different LGM boundary conditions associated with the ice sheet reconstruction (e.g., changes of elevation, bathymetry, and land-sea mask).
Abstract: . Changes in water mass distribution are considered to be a significant contributor to the atmospheric CO2 concentration drop to around 186 ppm recorded during the Last Glacial Maximum (LGM). Yet simulating a glacial Atlantic Meridional Overturning Circulation (AMOC) in agreement with paleotracer data remains a challenge, with most models from previous Paleoclimate Modelling Intercomparison Project (PMIP) phases showing a tendency to simulate a strong and deep North Atlantic Deep Water (NADW) instead of the shoaling inferred from proxy records of water mass distribution. Conversely, the simulated Antarctic Bottom Water (AABW) is often reduced compared to its pre-industrial volume, and the Atlantic Ocean stratification is underestimated with respect to paleoproxy data. Inadequate representation of surface conditions, driving deep convection around Antarctica, may explain inaccurately simulated bottom water properties in the Southern Ocean. We investigate here the impact of a range of surface conditions in the Southern Ocean in the iLOVECLIM model using nine simulations obtained with different LGM boundary conditions associated with the ice sheet reconstruction (e.g., changes of elevation, bathymetry, and land–sea mask) and/or modeling choices related to sea-ice export, formation of salty brines, and freshwater input.
Based on model–data comparison of sea-surface temperatures and sea ice, we find that only simulations with a cold Southern Ocean and a quite extensive sea-ice cover show an improved agreement with proxy records of sea ice, despite systematic model biases in the seasonal and regional patterns. We then show that the only simulation which does not display a much deeper NADW is obtained by parameterizing the sinking of brines along Antarctica, a modeling choice reducing the open-ocean convection in the Southern Ocean. These results highlight the importance of the representation of convection processes, which have a large impact on the water mass properties, while the choice of boundary conditions appears secondary for the model resolution and variables considered in this study.
17 citations
Cites background or methods from "The PMIP4 Last Glacial Maximum expe..."
...…differences between “Cold P2” and “Warm P2” suggest that, while iLOVECLIM generally simulates a more modest global SAT anomaly than other PMIP4 models (Kageyama et al., 2021), modeling choices related to the glacial temperature profiles used in the radiative code can induce a very significant…...
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...S1 and S2 of Kageyama et al., 2021)....
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...Compared to other PMIP4 models, iLOVECLIM simulates a quite-warm glacial climate, in agreement with previous evaluations (Roche et al., 2007): Kageyama et al. (2021) shows that half of the PMIP4 models simulate a LGM cooling in the −3.7 to −4 ◦C range, while three colder models simulate a larger…...
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...Indeed, we ran two simulations under the PMIP4 experimental design (“P4-G” and “P4-I”, both also used in Kageyama et al., 2021) and three under the PMIP2 one (“New P2”, “Cold P2”, and “Warm P2”)....
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...…was obtained thanks to a field reconstruction of LGM temperatures using data assimilation in the Community Earth System Model (CESM), an innovative method which is not freed from potential model biases, with CESM being the coldest model out of the PMIP4 ensemble in Kageyama et al. (2021)....
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References
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TL;DR: A new version of the general circulation model CNRM-CM has been developed jointly by CNRMs-GAME (Centre National de Recherches Meteorologiques-Groupe d'etudes de l’Atmosphere Meteorologique) and Cerfacs as discussed by the authors in order to contribute to phase 5 of the Coupled Model Intercomparison Project (CMIP5).
Abstract: A new version of the general circulation model CNRM-CM has been developed jointly by CNRM-GAME (Centre National de Recherches Meteorologiques—Groupe d’etudes de l’Atmosphere Meteorologique) and Cerfacs (Centre Europeen de Recherche et de Formation Avancee) in order to contribute to phase 5 of the Coupled Model Intercomparison Project (CMIP5). The purpose of the study is to describe its main features and to provide a preliminary assessment of its mean climatology. CNRM-CM5.1 includes the atmospheric model ARPEGE-Climat (v5.2), the ocean model NEMO (v3.2), the land surface scheme ISBA and the sea ice model GELATO (v5) coupled through the OASIS (v3) system. The main improvements since CMIP3 are the following. Horizontal resolution has been increased both in the atmosphere (from 2.8° to 1.4°) and in the ocean (from 2° to 1°). The dynamical core of the atmospheric component has been revised. A new radiation scheme has been introduced and the treatments of tropospheric and stratospheric aerosols have been improved. Particular care has been devoted to ensure mass/water conservation in the atmospheric component. The land surface scheme ISBA has been externalised from the atmospheric model through the SURFEX platform and includes new developments such as a parameterization of sub-grid hydrology, a new freezing scheme and a new bulk parameterisation for ocean surface fluxes. The ocean model is based on the state-of-the-art version of NEMO, which has greatly progressed since the OPA8.0 version used in the CMIP3 version of CNRM-CM. Finally, the coupling between the different components through OASIS has also received a particular attention to avoid energy loss and spurious drifts. These developments generally lead to a more realistic representation of the mean recent climate and to a reduction of drifts in a preindustrial integration. The large-scale dynamics is generally improved both in the atmosphere and in the ocean, and the bias in mean surface temperature is clearly reduced. However, some flaws remain such as significant precipitation and radiative biases in many regions, or a pronounced drift in three dimensional salinity.
1,193 citations
TL;DR: In this paper, a new model of the last deglaciation event of the Late Quaternary ice age is described and denoted as ICE-6G_C (VM5a), which has been explicitly refined by applying all of the available Global Positioning System (GPS) measurements of vertical motion of the crust that may be brought to bear to constrain the thickness of local ice cover as well as the timing of its removal.
Abstract: A new model of the last deglaciation event of the Late Quaternary ice age is here described and denoted as ICE-6G_C (VM5a). It differs from previously published models in this sequence in that it has been explicitly refined by applying all of the available Global Positioning System (GPS) measurements of vertical motion of the crust that may be brought to bear to constrain the thickness of local ice cover as well as the timing of its removal. Additional space geodetic constraints have also been applied to specify the reference frame within which the GPS data are described. The focus of the paper is upon the three main regions of Last Glacial Maximum ice cover, namely, North America, Northwestern Europe/Eurasia, and Antarctica, although Greenland and the British Isles will also be included, if peripherally, in the discussion. In each of the three major regions, the model predictions of the time rate of change of the gravitational field are also compared to that being measured by the Gravity Recovery and Climate Experiment satellites as an independent means of verifying the improvement of the model achieved by applying the GPS constraints. Several aspects of the global characteristics of this new model are also discussed, including the nature of relative sea level history predictions at far-field locations, in particular the Caribbean island of Barbados, from which especially high-quality records of postglacial sea level change are available but which records were not employed in the development of the model. Although ICE-6G_C (VM5a) is a significant improvement insofar as the most recently available GPS observations are concerned, comparison of model predictions with such far-field relative sea level histories enables us to identify a series of additional improvements that should follow from a further stage of model iteration.
902 citations
TL;DR: The Palaeoclimate Modelling Intercomparison Project (POMIP) as discussed by the authors evaluated model performance against the geologic record of environmental responses to climate changes and provided a unique opportunity to test model performance outside this limited climate range.
Abstract: There is large uncertainty about the magnitude of warming and how rainfall patterns will change in response to any given scenario of future changes in atmospheric composition and land use. The models used for future climate projections were developed and calibrated using climate observations from the past 40 years. The geologic record of environmental responses to climate changes provides a unique opportunity to test model performance outside this limited climate range. Evaluation of model simulations against palaeodata shows that models reproduce the direction and large-scale patterns of past changes in climate, but tend to underestimate the magnitude of regional changes. As part of the effort to reduce model-related uncertainty and produce more reliable estimates of twenty-first century climate, the Palaeoclimate Modelling Intercomparison Project is systematically applying palaeoevaluation techniques to simulations of the past run with the models used to make future projections. This evaluation will provide assessments of model performance, including whether a model is sufficiently sensitive to changes in atmospheric composition, as well as providing estimates of the strength of biosphere and other feedbacks that could amplify the model response to these changes and modify the characteristics of climate variability.
852 citations
"The PMIP4 Last Glacial Maximum expe..." refers methods or result in this paper
...…that large-scale climate features, such as the ratio of changes in land–sea temperature, high-latitude temperature amplification and precipitation scaling with temperature, were broadly consistent with modern observations (Braconnot et al., 2012; Izumi et al., 2013; Harrison et al., 2014, 2015)....
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...…are similar in magnitude (although opposite in sign) to the signals seen in future projections and have been shown to be consistent with climate observations for the historic period and reconstructions for the LGM (Braconnot et al., 2012; Izumi et al., 2013; Harrison et al., 2014, 2015)....
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...Past, 17, 1065–1089, 2021 ter agreement than with the reconstructions from Bartlein et al. (2011) and MARGO Project Members (2009) used to evaluate these features previously (Braconnot et al., 2012; Izumi et al., 2013; Harrison et al., 2014, 2015) for the tropical and global averages....
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...It is the most recent global cold extreme and as such has been widely documented and used for benchmarking state-of-the-art climate models (Braconnot et al., 2012; Harrison et al., 2014, 2015)....
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University of Oregon1, Macquarie University2, University of Bristol3, University of Wyoming4, University of the Algarve5, École Polytechnique Fédérale de Lausanne6, University of Ottawa7, University of Minnesota8, Centre national de la recherche scientifique9, University of Helsinki10, Tallinn University11, United States Geological Survey12, University of Wisconsin-Madison13, Chinese Academy of Sciences14
TL;DR: In this article, the mid-Holocene (MH, around 6 ka) and the Last Glacial Maximum (LGM, around 21 ka) were compared with palaeoclimate simulations currently being carried out as part of the fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change.
Abstract: Subfossil pollen and plant macrofossil data derived from 14 C-dated sediment profiles can provide quantitative information on glacial and interglacial cli- mates. 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 recon- structions 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
554 citations
"The PMIP4 Last Glacial Maximum expe..." refers background or methods or result in this paper
...The magnitude of the summer cooling is more consistent between the PMIP4 simulations and the Cleator et al. (2020) reconstructions than between the PMIP3 simulations and the Bartlein et al. (2011) reconstructions in North America, Eu- Clim....
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...The ranges of PMIP3 and PMIP4 results are broadly similar over this region, and there are the same number of models (four) within the reconstructed range of Cleator et al. (2020), while no model result was compatible with the Bartlein et al. (2011) reconstructions....
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...…in MAT consistent with the reconstructions (and reconstruction uncertainty), the globally averaged change in MAT is between −5.7 and −3.7 ◦C using the Bartlein et al. (2011), between −6.7 and −4.6 ◦C us- ing the Cleator et al. (2020) datasets, between −4.7 and −3.3 ◦C for the Tierney et al.…...
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...The simulated cooling in winter temperature is smaller than that indicated by the Bartlein et al. (2011) reconstructions (Fig....
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...Although the Bartlein et al. (2011) dataset has good coverage for some regions, coverage was sparse in the tropics, and there were no reconstructions of LGM climate for Australia....
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TL;DR: The model has a climate sensitivity to a doubling of CO2 over preindustrial conditions of 2.77 K, maintaining the previously identified highly nonlinear global mean response to increasing CO2 forcing, which nonetheless can be represented by a simple two‐layer model.
Abstract: A new release of the Max Planck Institute for Meteorology Earth System Model version 1.2 (MPI‐ESM1.2) is presented. The development focused on correcting errors in and improving the physical processes representation, as well as improving the computational performance, versatility, and overall user friendliness. In addition to new radiation and aerosol parameterizations of the atmosphere, several relatively large, but partly compensating, coding errors in the model's cloud, convection, and turbulence parameterizations were corrected. The representation of land processes was refined by introducing a multilayer soil hydrology scheme, extending the land biogeochemistry to include the nitrogen cycle, replacing the soil and litter decomposition model and improving the representation of wildfires. The ocean biogeochemistry now represents cyanobacteria prognostically in order to capture the response of nitrogen fixation to changing climate conditions and further includes improved detritus settling and numerous other refinements. As something new, in addition to limiting drift and minimizing certain biases, the instrumental record warming was explicitly taken into account during the tuning process. To this end, a very high climate sensitivity of around 7 K caused by low‐level clouds in the tropics as found in an intermediate model version was addressed, as it was not deemed possible to match observed warming otherwise. As a result, the model has a climate sensitivity to a doubling of CO2 over preindustrial conditions of 2.77 K, maintaining the previously identified highly nonlinear global mean response to increasing CO2 forcing, which nonetheless can be represented by a simple two‐layer model.
542 citations