Surface warming and wetting due to methane’s long-wave radiative effects muted by short-wave absorption

Details

• Journal Title:
  Nature Geoscience
• Personal Author:
  Allen, Robert J. ; Zhao, Xueying ; Randles, Cynthia A. ; Kramer, Ryan J. ; Samset, Bjørn H. ; Smith, Christopher J.
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research)
• Description:
  Although 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.
• Keywords:
  General Earth and Planetary Sciences
• Source:
  Nature Geoscience, 16(4), 314-320
• DOI:
  https://doi.org/10.1038/s41561-023-01144-z
• ISSN:
  1752-0894 ; 1752-0908
• Format:
  PDF
• Publisher:
  Springer Science and Business Media LLC
• Document Type:
  Journal Article
• Funding:
  Grant no. NA18OAR4310269
• License:
  https://creativecommons.org/licenses/by/4.0
• Rights Information:
  CC BY
• Compliance:
  Library
• Main Document Checksum:
  urn:sha256:f757e49086303e975b24fb17a0bc7b5d32f71c4545264d8f093d7d367da04d0e
• Download URL:
  https://repository.library.noaa.gov/view/noaa/52461/noaa_52461_DS1.pdf
• File Type:
  [PDF - 10.47 MB ]