Surface warming and wetting due to methane’s long-wave radiative effects muted by short-wave absorption
Allen, R.J.; Zhao, X.; Randles, C.A.; Kramer, R.J.; Samset, B.H.; Smith, C.J. (2023). Surface warming and wetting due to methane’s long-wave radiative effects muted by short-wave absorption. Nature Geoscience 16(4): 314-320. https://dx.doi.org/10.1038/s41561-023-01144-z
In: Nature Geoscience. Nature Publishing Group: London. ISSN 1752-0894; e-ISSN 1752-0908, meer
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| Auteurs | | Top |
- Allen, R.J.
- Zhao, X.
- Randles, C.A.
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- Kramer, R.J.
- Samset, B.H.
- Smith, C.J.
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| Abstract |
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. |
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