@article{0928be748c7046bf97b6acacb396a524,
title = "Assessment of Equilibrium Climate Sensitivity of the Community Earth System Model Version 2 Through Simulation of the Last Glacial Maximum",
abstract = "The upper end of the equilibrium climate sensitivity (ECS) has increased substantially in the latest Coupled Model Intercomparison Projects phase 6 with eight models (as of this writing) reporting an ECS > 5°C. The Community Earth System Model version 2 (CESM2) is one such high-ECS model. Here we perform paleoclimate simulations of the Last Glacial Maximum (LGM) using CESM2 to examine whether its high ECS is realistic. We find that the simulated LGM global mean temperature decrease exceeds 11°C, greater than both the cooling estimated from proxies and simulated by an earlier model version (CESM1). The large LGM cooling in CESM2 is attributed to a strong shortwave cloud feedback in the newest atmosphere model. Our results indicate that the high ECS of CESM2 is incompatible with LGM constraints and that the projected future warming in CESM2, and models with a similarly high ECS, is thus likely too large.",
keywords = "cloud feedback, equilibrium climate sensitivity, last glacial maximum",
author = "Jiang Zhu and Otto-Bliesner, {Bette L.} and Brady, {Esther C.} and Poulsen, {Christopher J.} and Tierney, {Jessica E.} and Marcus Lofverstrom and Pedro DiNezio",
note = "Funding Information: The authors thank the Editor, Hui Su, and Deepak Chandan and an anonymous reviewer for their constructive comments. This work was supported by Heising‐Simons Foundation grant #2016‐15 to C. Poulsen and J. Tierney, Heising‐Simons Foundation grant #2016‐12 and National Science Foundation grant 2002397 to C. Poulsen, and National Science Foundation grant AGS‐1602301 to J. Tierney. CESM model code is available through the National Center for Atmospheric Research GitHub repository ( https://github.com/ESCOMP/CESM/releases/tag/cesm2.1.1 ). The CESM project is supported primarily by the National Science Foundation (NSF). This material is based upon work supported by the National Center for Atmospheric Research, which is a major facility sponsored by the NSF under Cooperative Agreement No. 1852977. The authors thank M. Zelinka for making available the updated forcing‐feedback analysis of CMIP6 models. Publisher Copyright: {\textcopyright} 2021. The Authors.",
year = "2021",
month = feb,
doi = "10.1029/2020GL091220",
language = "English (US)",
volume = "48",
journal = "Geophysical Research Letters",
issn = "0094-8276",
publisher = "American Geophysical Union",
number = "3",
}