Response of winter climate and extreme weather to projected Arctic sea-ice loss in very large-ensemble climate model simulations

Abstract Very large (~2000 members) initial-condition ensemble simulations have been performed to advance understanding of mean climate and extreme weather responses to projected Arctic sea-ice loss under 2 °C global warming above preindustrial levels. These simulations better sample internal atmosp...

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Bibliographic Details
Published in:npj Climate and Atmospheric Science
Main Authors: Kunhui Ye, Tim Woollings, Sarah N. Sparrow, Peter A. G. Watson, James A. Screen
Format: Article in Journal/Newspaper
Language:English
Published: Nature Portfolio 2024
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Online Access:https://doi.org/10.1038/s41612-023-00562-5
https://doaj.org/article/b51a1204a9654aed9e9f5fd169bf7386
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Summary:Abstract Very large (~2000 members) initial-condition ensemble simulations have been performed to advance understanding of mean climate and extreme weather responses to projected Arctic sea-ice loss under 2 °C global warming above preindustrial levels. These simulations better sample internal atmospheric variability and extremes for each model compared to those from the Polar Amplification Model Intercomparison Project (PAMIP). The mean climate response is mostly consistent with that from the PAMIP multi-model ensemble, including tropospheric warming, reduced midlatitude westerlies and storm track activity, an equatorward shift of the eddy-driven jet and increased mid-to-high latitude blocking. Two resolutions of the same model exhibit significant differences in the stratospheric circulation response; however, these differences only weakly modulate the tropospheric response. The response of temperature and precipitation extremes largely follows the seasonal-mean response. Sub-sampling confirms that large ensembles (e.g. ≥400) are needed to robustly estimate the seasonal-mean large-scale circulation response, and very large ensembles (e.g. ≥1000) for regional climate and extremes.