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Title: Observational constraints on mixed-phase clouds imply higher climate sensitivity

Global climate model (GCM) estimates of the equilibrium global mean surface temperature response to a doubling of atmospheric CO 2, measured by the equilibrium climate sensitivity (ECS), range from 2.0° to 4.6°C. Clouds are among the leading causes of this uncertainty. Here, in this paper, we show that the ECS can be up to 1.3°C higher in simulations where mixed-phase clouds consisting of ice crystals and supercooled liquid droplets are constrained by global satellite observations. The higher ECS estimates are directly linked to a weakened cloud-phase feedback arising from a decreased cloud glaciation rate in a warmer climate. Finally, we point out the need for realistic representations of the supercooled liquid fraction in mixed-phase clouds in GCMs, given the sensitivity of the ECS to the cloud-phase feedback.
Authors:
 [1] ;  [1] ;  [2]
  1. Yale Univ., New Haven, CT (United States). Department of Geology and Geophysics
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Program for Climate Model Diagnosis and Intercomparison
Publication Date:
Report Number(s):
LLNL-JRNL-735511
Journal ID: ISSN 0036-8075
Grant/Contract Number:
AC52-07NA27344; SC0012580
Type:
Published Article
Journal Name:
Science
Additional Journal Information:
Journal Volume: 352; Journal Issue: 6282; Journal ID: ISSN 0036-8075
Publisher:
AAAS
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES
OSTI Identifier:
1355851
Alternate Identifier(s):
OSTI ID: 1409950