Journal Article

Impacts of Antarctic Sea Ice Change on Global Warming Pattern Inferred From CMIP6 Intermodel Spread

Chen, Dake, Ying, Jun, Geng, Yu‐Fan, Xie, Shang‐Ping, Luo, Fengyun

2025

Overview

Global climate models generally project a robust decline in Antarctic sea ice (ASI) under increased atmospheric carbon dioxide (CO2) while an ASI expansion has been observed over the recent four decades. Motivated by the apparent model‐observation discrepancy, this study investigates the influences of ASI change on global warming pattern by exploiting the spread across models from Phase 6 of the Coupled Model Intercomparison Project (CMIP6). The results indicate a close intermodel relationship between ASI change and global sea surface warming pattern. Models with less ASI loss tend to produce a weaker warming globally, especially in the Southern Ocean, subtropical southeastern Pacific Ocean, and tropical Pacific Ocean. This extratropical teleconnection to the tropics agrees with the theory of cross‐equator energy transport. By correcting the modeled ASI change with observations, we can bring the SST warming pattern closer to observations, especially in the Southern Hemisphere and tropics. Plain Language Summary Over the past 40 years, Antarctic sea ice (ASI) has expanded despite the steady rise of atmospheric carbon dioxide (CO2). However, global climate models generally fail to replicate the ASI trend. Such a model‐observation discrepancy casts doubts on model projections of ocean surface warming pattern under greenhouse forcing. Here, we find a close intermodel relationship between the ASI change and the SST warming pattern across CMIP6 models, with positive intermodel spread in ASI tending to have weaker sea surface warming globally, especially in the Southern Ocean, the subtropical southeastern and the tropical Pacific Ocean. When the modeled ASI changes are adjusted to the observed ASI trend in the recent four decades, the model‐simulated warming pattern appears to be closer to observations. Key Points There is a significant negative relationship between Antarctic sea ice loss and global warming across CMIP6 models The impacts of Antarctic sea ice change on global warming pattern agree with cross‐equatorial energy transport theory Modeled global warming pattern is closer to observations by constraining the Antarctic sea ice change in the recent four decades

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: Antarctic sea ice / Carbon dioxide / Climate / Climate change / Climate models / Energy transport / Equator / Global climate / Global climate models / Global warming / Greenhouse effect / Intercomparison / Ocean models / Ocean surface / Ocean warming / ocean warming pattern / Oceans / Sea ice / Sea surface temperature / Sea surface warming / Southern Hemisphere / Southern Ocean / Surface temperature / Tropical environments