Structure and Performance of GFDL's CM4.0 Climate Model

Held, Isaac M.; Guo, Huan; Adcroft, Alistair; Dunne, John; Horowitz, Larry W.; Krasting, John P.; Shevliakova, Elena; Winton, Michael; Zhao, Ming; Bushuk, Mitchell; Wittenberg, Andrew T.; Wyman, Bruce; Xiang, Baoqiang; Zhang, R.; Anderson, W.; Balaji, V.; Donner, Leo J.; Dunne, Krista A.; Durachta, J.; Gauthier, Paul P. G.; Ginoux, Paul; Golaz, Jean‐Christophe; Griffies, Stephen M.; Hallberg, Robert; Harris, Lucas; Harrison, Matthew; Hurlin, William J.; John, Jasmin G.; Lin, Pu; Lin, Shian‐Jiann; Malyshev, Sergey; Menzel, Raymond; Milly, P. C. D.; Ming, Yi; Naik, Vaishali; Paynter, David; Paulot, Fabien; Rammaswamy, V.; Reichl, Brandon G.; Robinson, T.; Rosati, Anthony; Seman, Charles J.; Silvers, Levi G.; Underwood, Seth; Zadeh, Niki

doi:10.1029/2019ms001829

Cited by 271 publications

(252 citation statements)

References 99 publications

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“…Land vegetation is interactive, while glaciers and icecaps are prescribed. Improvements of the climatology and variability simulations of GFDL's CMIP6 generation CM4.0 have been documented by Held et al (2019).…”

Section: Introductionmentioning

confidence: 98%

Climate Sensitivity of GFDL's CM4.0

Winton

Adcroft

Dunne

et al. 2020

J Adv Model Earth Syst

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GFDL's new CM4.0 climate model has high transient and equilibrium climate sensitivities near the middle of the upper half of CMIP5 models. The CMIP5 models have been criticized for excessive sensitivity based on observations of present-day warming and heat uptake and estimates of radiative forcing. An ensemble of historical simulations with CM4.0 produces warming and heat uptake that are consistent with these observations under forcing that is at the middle of the assessed distribution. Energy budget-based methods for estimating sensitivities based on these quantities underestimate CM4.0's sensitivities when applied to its historical simulations. However, we argue using a simple attribution procedure that CM4.0's warming evolution indicates excessive transient sensitivity to greenhouse gases. This excessive sensitivity is offset prior to recent decades by excessive response to aerosol and land use changes. Plain Language SummaryWe evaluate the climate sensitivity of the Geophysical Fluid Dynamics Laboratory (GFDL) CM4.0 climate model. Climate sensitivity is an important factor determining the magnitude of future climate change under anthropogenic forcing. We find that CM4.0 is a high climate sensitivity model. A simple method for estimating climate sensitivity from historical changes significantly underestimates CM4.0's sensitivity when applied to CM4.0's historical simulation. However, more sophisticated methods that make use of the detailed evolution of global warming identify CM4.0 as most likely too sensitive to anthropogenic forcing. Key Points: • CM4.0 has high equilibrium and transient climate sensitivities, both near the CMIP5 75th percentile • The energy budget sensitivity estimation method significantly underestimates CM4.0's sensitivities • CM4.0's excessive warming over recent decades most likely indicates excessive transient sensitivity Correspondence to: M. Winton, Michael.Winton@noaa.gov Citation: Winton, M., Adcroft, A., Dunne, J. P., Held, I. M., Shevliakova, E., Zhao, M., et al. (2020). Climate sensitivity of GFDL's CM4.0.

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Section: Introductionmentioning

confidence: 98%

Climate Sensitivity of GFDL's CM4.0

Winton

Adcroft

Dunne

et al. 2020

J Adv Model Earth Syst

Self Cite

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“…1A) (19). Overestimating both the climate feedbacks and the aerosol forcing can result in a historical warming to present day that is similar as observed, but the temporal agreement with observations is poor, with little simulated warming until 1980 and too strong warming after [e.g., E3SM1 (20), UKESM1 (21), or GFDL-CM4 (22)].…”

Section: Resultsmentioning

confidence: 85%

“…This probably leads to future warming projections being biased high. Thus, the raw ensemble median and spread of future warming in CMIP6 (and therefore most other variables that scale to first order with global mean temperature) are not representative of a distribution constrained by observed trends, even if some of those models show a more realistic representation of processes in individual components than their CMIP5 predecessors (20)(21)(22). Conversely, CMIP6 models with climate sensitivity values that are within the IPCC AR5 likely range show warming trends much more consistent with the observations.…”

Section: Discussionmentioning

confidence: 99%

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Past warming trend constrains future warming in CMIP6 models

Stolpe¹,

Tokarska²,

Sippel³

et al. 2020

Preprint

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Future global warming estimates have been similar across past assessments, but several climate models of the latest Sixth Coupled Model Intercomparison Project (CMIP6) simulate much stronger warming, apparently inconsistent with past assessments. Here, we show that projected future warming is correlated with the simulated warming trend during recent decades across CMIP5 and CMIP6 models, enabling us to constrain future warming based on consistency with the observed warming. These findings carry important policy-relevant implications: The observationally constrained CMIP6 median warming in high emissions and ambitious mitigation scenarios is over 16 and 14% lower by 2050 compared to the raw CMIP6 median, respectively, and over 14 and 8% lower by 2090, relative to 1995-2014. Observationally constrained CMIP6 warming is consistent with previous assessments based on CMIP5 models, and in an ambitious mitigation scenario, the likely range is consistent with reaching the Paris Agreement target.

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“…Since CO 2 radiative forcing nearly scales with the logarithm of CO 2 concentration, the global temperature change in response to a doubling of CO 2 is estimated as half that reached in response to a quadrupling of CO 2 . To reduce contamination by fast model adjustments (Held et al, 2010;Winton et al, 2013), we perform the regression using 50-year means from years 51 to 300 as described by Winton et al (2019).…”

Section: 1029/2019gl085601mentioning

confidence: 99%

Revisiting the Impact of Sea Salt on Climate Sensitivity

Paulot

Paynter

Winton

et al. 2020

Geophysical Research Letters

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Recent laboratory and field studies point to an increase of sea salt aerosol (SSA) emissions with temperature, suggesting that SSA may lower climate sensitivity. We assess the impact of a strong (4.2% K −1) and weak (0.7% K −1) temperature response of SSA emissions on the climate sensitivity of the coupled climate model CM4. We find that the stronger temperature dependence improves the simulation of marine aerosol optical depth sensitivity to temperature and lowers CM4 Transient Climate Response (‐0.12 K) and Equilibrium Climate Sensitivity (‐0.5 K). At normalCO2 doubling, the higher SSA emission sensitivity causes a negative radiative feedback (‐0.125 normalWm−2K−1), which can only be partly explained by changes in the radiative effect of SSA (‐0.08 normalWm−2K−1). Stronger radiative feedbacks are dominated by more negative low‐level cloud feedbacks in the Northern Hemisphere, which are partly offset by more positive feedbacks in the Southern Hemisphere associated with a weaker Atlantic Meridional Overturning Circulation.

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Structure and Performance of GFDL's CM4.0 Climate Model

Cited by 271 publications

References 99 publications

Climate Sensitivity of GFDL's CM4.0

Climate Sensitivity of GFDL's CM4.0

Past warming trend constrains future warming in CMIP6 models

Revisiting the Impact of Sea Salt on Climate Sensitivity

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