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Reducing the uncertainty in subtropical cloud feedback
Author(s) -
Myers Timothy A.,
Norris Joel R.
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl067416
Subject(s) - cloud feedback , cloud forcing , shortwave , environmental science , subtropics , climate sensitivity , cloud cover , forcing (mathematics) , global warming , cloud computing , atmospheric sciences , climatology , positive feedback , climate change , climate model , negative feedback , computer science , radiative transfer , geology , physics , ecology , oceanography , biology , operating system , electrical engineering , engineering , quantum mechanics , voltage
Large uncertainty remains on how subtropical clouds will respond to anthropogenic climate change and therefore whether they will act as a positive feedback that amplifies global warming or negative feedback that dampens global warming by altering Earth's energy budget. Here we reduce this uncertainty using an observationally constrained formulation of the response of subtropical clouds to greenhouse forcing. The observed interannual sensitivity of cloud solar reflection to varying meteorological conditions suggests that increasing sea surface temperature and atmospheric stability in the future climate will have largely canceling effects on subtropical cloudiness, overall leading to a weak positive shortwave cloud feedback (0.4 ± 0.9 W m −2 K −1 ). The uncertainty of this observationally based approximation of the cloud feedback is narrower than the intermodel spread of the feedback produced by climate models. Subtropical cloud changes will therefore complement positive cloud feedbacks identified by previous work, suggesting that future global cloud changes will amplify global warming.