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Title: Stronger Arctic amplification produced by decreasing, not increasing, CO 2 concentrations
Abstract

Arctic amplification (AA), referring to the phenomenon of amplified warming in the Arctic compared to the warming in the rest of the globe, is generally attributed to the increasing concentrations of carbon dioxide (CO2) in the atmosphere. However, little attention has been paid to the mechanisms and quantitative variations of AA under decreasing levels of CO2, when cooling where the Arctic region is considerably larger than over the rest of the planet. Analyzing climate model experiments forced with a wide range of CO2concentrations (from 1/8× to 8×CO2, with respect to preindustrial levels), we show that AA indeed occurs under decreasing CO2concentrations, and it is stronger than AA under increasing CO2concentrations. Feedback analysis reveals that the Planck, lapse-rate, and albedo feedbacks are the main contributors to producing AAs forced by CO2increase and decrease, but the stronger lapse-rate feedback associated with decreasing CO2level gives rise to stronger AA. We further find that the increasing CO2concentrations delay the peak month of AA from November to December or January, depending on the forcing strength. In contrast, decreasing CO2levels cannot shift the peak of AA earlier than October, as a consequence of the maximum sea-ice increase in September which is independent of forcing strength. Such seasonality changes are also presented in the lapse-rate feedback, but do not appear in other feedbacks nor in the atmospheric and oceanic heat transport processeses. Our results highlight the strongly asymmetric responses of AA, as evidenced by the different changes in its intensity and seasonality, to the increasing and decreasing CO2concentrations. These findings have significant implications for understanding how carbon removal could impact the Arctic climate, ecosystems, and socio-economic activities.

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Award ID(s):
2234876
NSF-PAR ID:
10492495
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
IOP Publishing
Date Published:
Journal Name:
Environmental Research: Climate
Volume:
2
Issue:
4
ISSN:
2752-5295
Page Range / eLocation ID:
045001
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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