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Surface Warming and Wetting Due to Methane’s Longwave Radiative Effects Muted By Shortwave AbsorptionAlthough greenhouse gases absorb primarily long-wave radiation, they also absorb short-wave radiation. Recent studies have highlighted the importance of methane short-wave absorption, which enhances its stratospherically adjusted radiative forcing by up to ~ 15%. The corresponding climate impacts, however, have been only indirectly evaluated and thus remain largely unquantified. Here we present a systematic, unambiguous analysis using one model and separate simulations with and without methane short-wave absorption. We find that methane short-wave absorption counteracts ~30% of the surface warming associated with its long-wave radiative effects. An even larger impact occurs for precipitation as methane short-wave absorption offsets ~60% of the precipitation increase relative to its long-wave radiative effects. The methane short-wave-induced cooling is due largely to cloud rapid adjustments, including increased low-level clouds, which enhance the reflection of incoming short-wave radiation, and decreased high-level clouds, which enhance outgoing long-wave radiation. The cloud responses, in turn, are related to the profile of atmospheric solar heating and corresponding changes in temperature and relative humidity. Despite our findings, methane remains a potent contributor to global warming, and efforts to reduce methane emissions are vital for keeping global warming well below 2 °C above preindustrial values.
Document ID
20230009900
Acquisition Source
Goddard Space Flight Center
Document Type
Accepted Manuscript (Version with final changes)
Authors
Robert J. Allen ORCID
(University of California, Riverside Riverside, California, United States)
Xueying Zhao ORCID
(University of California, Riverside Riverside, California, United States)
Cynthia A. Randles ORCID
(UNEP International Methane Emission Observatory Paris, France)
Ryan J. Kramer ORCID
(University of Maryland, Baltimore County Baltimore, Maryland, United States)
Bjørn H. Samset ORCID
(Center for International Climate and Environmental Research Oslo, Norway)
Christopher J. Smith ORCID
(University of Leeds Leeds, United Kingdom)
Date Acquired
July 5, 2023
Publication Date
March 16, 2023
Publication Information
Publication: Nature Geoscience
Publisher: Nature Research
Volume: 16
Issue Publication Date: April 1, 2023
ISSN: 1752-0894
e-ISSN: 1752-0908
URL: https://www.nature.com/articles/s41561-023-01144-z
Subject Category
Meteorology and Climatology
Funding Number(s)
CONTRACT_GRANT: 80NSSC21K1968
CONTRACT_GRANT: 80GRC020D0003
CONTRACT_GRANT: 80NSSC22M0001
Distribution Limits
Public
Copyright
Portions of document may include copyright protected material.
Technical Review
External Peer Committee
Keywords
radiative forcing
methane
shortwave radiation
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