scholarly journals Assessment of Equilibrium Climate Sensitivity of the Community Earth System Model Version 2 Through Simulation of the Last Glacial Maximum

2021 ◽  
Vol 48 (3) ◽  
Author(s):  
Jiang Zhu ◽  
Bette L. Otto‐Bliesner ◽  
Esther C. Brady ◽  
Christopher J. Poulsen ◽  
Jessica E. Tierney ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Climate Sensitivity ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Equilibrium Climate Sensitivity ◽  
Last Glacial ◽  
Community Earth System Model ◽  
The Last Glacial Maximum ◽  
The Last Glacial

scholarly journals A global climatology of the ocean surface during the Last Glacial Maximum mapped on a regular grid (GLOMAP)

2021 ◽  
Vol 17 (2) ◽  
pp. 805-824
Author(s):  
André Paul ◽  
Stefan Mulitza ◽  
Rüdiger Stein ◽  
Martin Werner
Keyword(s):  
Sea Ice ◽  
Last Glacial Maximum ◽  
Climate Sensitivity ◽  
Ocean Surface ◽  
Glacial Maximum ◽  
Sea Ice Extent ◽  
Equilibrium Climate Sensitivity ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. We present a climatology of the near-sea-surface temperature (NSST) anomaly and the sea-ice extent during the Last Glacial Maximum (LGM, 23 000–19 000 years before present) mapped on a global regular 1∘×1∘ grid. It is an extension of the Glacial Atlantic Ocean Mapping (GLAMAP) reconstruction of the Atlantic NSST based on the faunal and floral assemblage data of the Multiproxy Approach for the Reconstruction of the Glacial Ocean Surface (MARGO) project and several recent estimates of the LGM sea-ice extent. Such a gridded climatology is highly useful for the visualization of the LGM climate, calculation of global and regional NSST averages, and estimation of the equilibrium climate sensitivity, as well as a boundary condition for atmospheric general circulation models. The gridding of the sparse NSST reconstruction was done in an optimal way using the Data-Interpolating Variational Analysis (DIVA) software, which takes into account the uncertainty in the reconstruction and includes the calculation of an error field. The resulting Glacial Ocean Map (GLOMAP) confirms the previous findings by the MARGO project regarding longitudinal and meridional NSST differences that were greater than today in all oceans. Taken at face value, the estimated global and tropical cooling would imply an equilibrium climate sensitivity at the lower end of the currently accepted range. However, because of anticipated changes in the seasonality and thermal structure of the upper ocean during the LGM as well as uneven spatial sampling, the estimated cooling and implied climate sensitivity are likely to be biased towards lower values.

scholarly journals A global climatology of the ocean surface during the Last Glacial Maximum mapped on a regular grid (GLOMAP)

2020 ◽  
Author(s):  
André Paul ◽  
Stefan Mulitza ◽  
Rüdiger Stein ◽  
Martin Werner
Keyword(s):  
Sea Ice ◽  
Last Glacial Maximum ◽  
Climate Sensitivity ◽  
Ocean Surface ◽  
Glacial Maximum ◽  
Sea Ice Extent ◽  
Equilibrium Climate Sensitivity ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. We present a climatology of the sea-surface temperature (SST) anomaly and the sea-ice extent during the Last Glacial Maximum (LGM, 23 000–19 000 years before present) mapped on a global regular 1° × 1° grid. It is an extension of the Glacial Atlantic Ocean Mapping (GLAMAP) reconstruction of the Atlantic SST based on the results of the Multiproxy Approach for the Reconstruction of the Glacial Ocean Surface (MARGO) project and several recent estimates of the LGM sea-ice extent. Such a gridded climatology is highly useful for the visualization of the LGM climate, calculation of global and regional SST averages and estimation of the equilibrium climate sensitivity, as well as a boundary condition for atmospheric general circulation models. The gridding of the sparse SST reconstruction was done in an optimal way using the Data-Interpolating Variational Analysis (DIVA) software, which takes into account the uncertainty on the reconstruction and includes the calculation of an error field. The resulting Glacial Ocean Map (GLOMAP) confirmed the previous findings by the MARGO project regarding longitudinal and meridional SST differences that were greater than today in all oceans and an equilibrium climate sensitivity at the lower end of the currently accepted range.

scholarly journals PMIP4 experiments using MIROC-ES2L Earth System Model

2020 ◽  
Author(s):  
Rumi Ohgaito ◽  
Akitomo Yamamoto ◽  
Tomohiro Hajima ◽  
Ryouta O'ishi ◽  
Manabu Abe ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Volcanic Eruptions ◽  
Earth System Model ◽  
Glacial Maximum ◽  
Ice Age ◽  
System Model ◽  
Earth System ◽  
Proxy Data ◽  
Last Glacial ◽  
Data Archives

Abstract. Following the protocol of the fourth phase of the Paleoclimate Modeling Intercomparison Project (PMIP4), we performed numerical experiments targeting distinctive past time periods using the Model for Interdisciplinary Research on Climate Earth System Model (MIROC-ES2L), which is an Earth System Model. Setup and basic performance of the experiments are presented. The Last Glacial Maximum was one of the most extreme climate states during the Quaternary and conducting numerical modeling experiments of this period has long been a challenge for the paleoclimate community. We conducted a Last Glacial Maximum experiment with a long spin-up of nearly 9,000 years. Globally, there is reasonable agreement between the anomalies relative to present day derived from model climatology and those derived from proxy data archives while some regional discrepancies remain. By changing orbital and greenhouse gas forcings, we conducted experiments for two interglacial periods: 6,000 and 127,000 years before present. Model anomalies relative to present day are qualitatively consistent with variations in solar forcing. However, anomalies in the model are smaller than those derived from proxy data archives, suggesting that processes that play a role in past interglacial climates are still missing in this state-of-the-art model. We conducted transient simulations from 850 CE to 1850 CE and from 1850 CE to 2014 CE. Cooling in the model indicates clear responses to huge volcanic eruptions, which are consistent with paleo-proxy data. The contrast between cooling during the Little Ice Age and warming during the 20th to 21st centuries is well represented at the multi-decadal time scale.

scholarly journals High Climate Sensitivity in the Community Earth System Model Version 2 (CESM2)

2019 ◽  
Vol 46 (14) ◽  
pp. 8329-8337 ◽  
Author(s):  
A. Gettelman ◽  
C. Hannay ◽  
J. T. Bacmeister ◽  
R. B. Neale ◽  
A. G. Pendergrass ◽  
...  
Keyword(s):  
Climate Sensitivity ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Model Version ◽  
Community Earth System Model

scholarly journals Ocean (de)oxygenation from the Last Glacial Maximum to the twenty-first century: insights from Earth System models

2017 ◽  
Vol 375 (2102) ◽  
pp. 20160323 ◽  
Author(s):  
L. Bopp ◽  
L. Resplandy ◽  
A. Untersee ◽  
P. Le Mezo ◽  
M. Kageyama
Keyword(s):  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Earth System ◽  
Short Term ◽  
System Models ◽  
Last Glacial ◽  
Tropical Oceans ◽  
Earth System Models ◽  
The Last Glacial Maximum ◽  
The Last Glacial

All Earth System models project a consistent decrease in the oxygen content of oceans for the coming decades because of ocean warming, reduced ventilation and increased stratification. But large uncertainties for these future projections of ocean deoxygenation remain for the subsurface tropical oceans where the major oxygen minimum zones are located. Here, we combine global warming projections, model-based estimates of natural short-term variability, as well as data and model estimates of the Last Glacial Maximum (LGM) ocean oxygenation to gain some insights into the major mechanisms of oxygenation changes across these different time scales. We show that the primary uncertainty on future ocean deoxygenation in the subsurface tropical oceans is in fact controlled by a robust compensation between decreasing oxygen saturation (O 2sat ) due to warming and decreasing apparent oxygen utilization (AOU) due to increased ventilation of the corresponding water masses. Modelled short-term natural variability in subsurface oxygen levels also reveals a compensation between O 2sat and AOU, controlled by the latter. Finally, using a model simulation of the LGM, reproducing data-based reconstructions of past ocean (de)oxygenation, we show that the deoxygenation trend of the subsurface ocean during deglaciation was controlled by a combination of warming-induced decreasing O 2sat and increasing AOU driven by a reduced ventilation of tropical subsurface waters. This article is part of the themed issue ‘Ocean ventilation and deoxygenation in a warming world’.

Spatial Decomposition of Climate Feedbacks in the Community Earth System Model

2013 ◽  
Vol 26 (11) ◽  
pp. 3544-3561 ◽  
Author(s):  
A. Gettelman ◽  
J. E. Kay ◽  
J. T. Fasullo
Keyword(s):  
Climate Sensitivity ◽  
Earth System Model ◽  
Cloud Feedback ◽  
System Model ◽  
Storm Tracks ◽  
Cloud Base ◽  
Earth System ◽  
Cloud Feedbacks ◽  
Stratiform Clouds ◽  
Community Earth System Model

Abstract An ensemble of simulations from different versions of the Community Atmosphere Model in the Community Earth System Model (CESM) is used to investigate the processes responsible for the intermodel spread in climate sensitivity. In the CESM simulations, the climate sensitivity spread is primarily explained by shortwave cloud feedbacks on the equatorward flank of the midlatitude storm tracks. Shortwave cloud feedbacks have been found to explain climate sensitivity spread in previous studies, but the location of feedback differences was in the subtropics rather than in the storm tracks as identified in CESM. The cloud-feedback relationships are slightly stronger in the winter hemisphere. The spread in climate sensitivity in this study is related both to the cloud-base state and to the cloud feedbacks. Simulated climate sensitivity is correlated with cloud-fraction changes on the equatorward side of the storm tracks, cloud condensate in the storm tracks, and cloud microphysical state on the poleward side of the storm tracks. Changes in the extent and water content of stratiform clouds (that make up cloud feedback) are regulated by the base-state vertical velocity, humidity, and deep convective mass fluxes. Within the storm tracks, the cloud-base state affects the cloud response to CO2-induced temperature changes and alters the cloud feedbacks, contributing to climate sensitivity spread within the CESM ensemble.

scholarly journals Can the Last Glacial Maximum constrain climate sensitivity?

2012 ◽  
Vol 39 (24) ◽  
Author(s):  
J. C. Hargreaves ◽  
J. D. Annan ◽  
M. Yoshimori ◽  
A. Abe‐Ouchi
Keyword(s):  
Last Glacial Maximum ◽  
Climate Sensitivity ◽  
Glacial Maximum ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

scholarly journals An improved land biosphere module for use in the DCESS Earth system model (version 1.1) with application to the last glacial termination

2017 ◽  
Vol 10 (9) ◽  
pp. 3481-3498
Author(s):  
Roland Eichinger ◽  
Gary Shaffer ◽  
Nelson Albarrán ◽  
Maisa Rojas ◽  
Fabrice Lambert
Keyword(s):  
Carbon Cycling ◽  
Earth System Model ◽  
Cold Climate ◽  
System Model ◽  
Earth System ◽  
Proxy Data ◽  
Last Glacial ◽  
Transition Functions ◽  
Vegetation Zones ◽  
The Last Glacial

Abstract. Interactions between the land biosphere and the atmosphere play an important role for the Earth's carbon cycle and thus should be considered in studies of global carbon cycling and climate. Simple approaches are a useful first step in this direction but may not be applicable for certain climatic conditions. To improve the ability of the reduced-complexity Danish Center for Earth System Science (DCESS) Earth system model DCESS to address cold climate conditions, we reformulated the model's land biosphere module by extending it to include three dynamically varying vegetation zones as well as a permafrost component. The vegetation zones are formulated by emulating the behaviour of a complex land biosphere model. We show that with the new module, the size and timing of carbon exchanges between atmosphere and land are represented more realistically in cooling and warming experiments. In particular, we use the new module to address carbon cycling and climate change across the last glacial transition. Within the constraints provided by various proxy data records, we tune the DCESS model to a Last Glacial Maximum state and then conduct transient sensitivity experiments across the transition under the application of explicit transition functions for high-latitude ocean exchange, atmospheric dust, and the land ice sheet extent. We compare simulated time evolutions of global mean temperature, pCO2, atmospheric and oceanic carbon isotopes as well as ocean dissolved oxygen concentrations with proxy data records. In this way we estimate the importance of different processes across the transition with emphasis on the role of land biosphere variations and show that carbon outgassing from permafrost and uptake of carbon by the land biosphere broadly compensate for each other during the temperature rise of the early last deglaciation.

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