Do Southern Ocean Cloud Feedbacks Matter for 21st Century Warming?. Issue 24 (21st December 2017)

• Record Type: Journal Article
• Authors: Frey, W. R.; Maroon, E. A.; Pendergrass, A. G.; Kay, J. E.
• Is Part Of: Geophysical research letters. Volume 44:Issue 24(2017)
• Page Start: 12, 447
• Page End: 12, 456
• Publication Date: 2017-12-21
• Subjects: equilibrium climate sensitivity -- ocean heat uptake -- cloud feedback; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2017GL076339
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Cloud phase improvements in a state‐of‐the‐art climate model produce a large 1.5 K increase in equilibrium climate sensitivity (ECS, the surface warming in response to instantaneously doubled CO2 ) via extratropical shortwave cloud feedbacks. Here we show that the same model improvements produce only a small surface warming increase in a realistic 21st century emissions scenario. The small 21st century warming increase is attributed to extratropical ocean heat uptake. Southern Ocean mean‐state circulation takes up heat while a slowdown in North Atlantic circulation acts as a feedback to slow surface warming. Persistent heat uptake by extratropical oceans implies that extratropical cloud biases may not be as important to 21st century warming as biases in other regions. Observational constraints on cloud phase and shortwave radiation that produce a large ECS increase do not imply large changes in 21st century warming. Key Points: Modified extratropical radiative feedbacks increase equilibrium climate sensitivity by 1.5 K, but hardly impact 21st century warming Energy input by extratropical shortwave cloud feedbacks is taken up by the ocean and moved to depth, delaying transient surface warming Extratropical cloud biases may not be as important to transient warming as biases in other regions due to extratropical ocean heat uptake