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

A. Gettelman; C. Hannay; J. T. Bacmeister; R. B. Neale; A. G. Pendergrass; G. Danabasoglu; J. F. Lamarque; J. T. Fasullo; D. A. Bailey; D. M. Lawrence; M. J. Mills

doi:10.1029/2019GL083978

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

A. Gettelman, C. Hannay, J. T. Bacmeister, R. B. Neale, A. G. Pendergrass, G. Danabasoglu, J. F. Lamarque, J. T. Fasullo, D. A. Bailey, D. M. Lawrence, M. J. Mills

National Center for Atmospheric Research

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308 Scopus citations

Abstract

The Community Earth System Model Version 2 (CESM2) has an equilibrium climate sensitivity (ECS) of 5.3 K. ECS is an emergent property of both climate feedbacks and aerosol forcing. The increase in ECS over the previous version (CESM1) is the result of cloud feedbacks. Interim versions of CESM2 had a land model that damped ECS. Part of the ECS change results from evolving the model configuration to reproduce the long-term trend of global and regional surface temperature over the twentieth century in response to climate forcings. Changes made to reduce sensitivity to aerosols also impacted cloud feedbacks, which significantly influence ECS. CESM2 simulations compare very well to observations of present climate. It is critical to understand whether the high ECS, outside the best estimate range of 1.5–4.5 K, is plausible.

Original language	English
Pages (from-to)	8329-8337
Number of pages	9
Journal	Geophysical Research Letters
Volume	46
Issue number	14
DOIs	https://doi.org/10.1029/2019GL083978
State	Published - 2019

Keywords

climate models
climate sensitivity

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10.1029/2019GL083978

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title = "High Climate Sensitivity in the Community Earth System Model Version 2 (CESM2)",

abstract = "The Community Earth System Model Version 2 (CESM2) has an equilibrium climate sensitivity (ECS) of 5.3 K. ECS is an emergent property of both climate feedbacks and aerosol forcing. The increase in ECS over the previous version (CESM1) is the result of cloud feedbacks. Interim versions of CESM2 had a land model that damped ECS. Part of the ECS change results from evolving the model configuration to reproduce the long-term trend of global and regional surface temperature over the twentieth century in response to climate forcings. Changes made to reduce sensitivity to aerosols also impacted cloud feedbacks, which significantly influence ECS. CESM2 simulations compare very well to observations of present climate. It is critical to understand whether the high ECS, outside the best estimate range of 1.5–4.5 K, is plausible.",

keywords = "climate models, climate sensitivity",

author = "A. Gettelman and C. Hannay and Bacmeister, \{J. T.\} and Neale, \{R. B.\} and Pendergrass, \{A. G.\} and G. Danabasoglu and Lamarque, \{J. F.\} and Fasullo, \{J. T.\} and Bailey, \{D. A.\} and Lawrence, \{D. M.\} and Mills, \{M. J.\}",

year = "2019",

doi = "10.1029/2019GL083978",

language = "English",

volume = "46",

pages = "8329--8337",

journal = "Geophysical Research Letters",

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publisher = "John Wiley and Sons Inc.",

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TY - JOUR

T1 - High Climate Sensitivity in the Community Earth System Model Version 2 (CESM2)

AU - Gettelman, A.

AU - Hannay, C.

AU - Bacmeister, J. T.

AU - Neale, R. B.

AU - Pendergrass, A. G.

AU - Danabasoglu, G.

AU - Lamarque, J. F.

AU - Fasullo, J. T.

AU - Bailey, D. A.

AU - Lawrence, D. M.

AU - Mills, M. J.

PY - 2019

Y1 - 2019

N2 - The Community Earth System Model Version 2 (CESM2) has an equilibrium climate sensitivity (ECS) of 5.3 K. ECS is an emergent property of both climate feedbacks and aerosol forcing. The increase in ECS over the previous version (CESM1) is the result of cloud feedbacks. Interim versions of CESM2 had a land model that damped ECS. Part of the ECS change results from evolving the model configuration to reproduce the long-term trend of global and regional surface temperature over the twentieth century in response to climate forcings. Changes made to reduce sensitivity to aerosols also impacted cloud feedbacks, which significantly influence ECS. CESM2 simulations compare very well to observations of present climate. It is critical to understand whether the high ECS, outside the best estimate range of 1.5–4.5 K, is plausible.

AB - The Community Earth System Model Version 2 (CESM2) has an equilibrium climate sensitivity (ECS) of 5.3 K. ECS is an emergent property of both climate feedbacks and aerosol forcing. The increase in ECS over the previous version (CESM1) is the result of cloud feedbacks. Interim versions of CESM2 had a land model that damped ECS. Part of the ECS change results from evolving the model configuration to reproduce the long-term trend of global and regional surface temperature over the twentieth century in response to climate forcings. Changes made to reduce sensitivity to aerosols also impacted cloud feedbacks, which significantly influence ECS. CESM2 simulations compare very well to observations of present climate. It is critical to understand whether the high ECS, outside the best estimate range of 1.5–4.5 K, is plausible.

KW - climate models

KW - climate sensitivity

UR - https://www.scopus.com/pages/publications/85069816427

U2 - 10.1029/2019GL083978

DO - 10.1029/2019GL083978

M3 - Article

AN - SCOPUS:85069816427

SN - 0094-8276

VL - 46

SP - 8329

EP - 8337

JO - Geophysical Research Letters

JF - Geophysical Research Letters

IS - 14

ER -

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

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Keywords

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