Do Southern Ocean Cloud Feedbacks Matter for 21st-Century Warming?

TitleDo Southern Ocean Cloud Feedbacks Matter for 21st-Century Warming?
Publication TypeJournal Article
Year of Publication2018
JournalGeophysical Research Letters
Volume44
Number24
Pages12,447-12,456
Date Published11/2018
Abstract / Summary

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.

URLhttp://dx.doi.org/10.1002/2017gl076339
DOI10.1002/2017gl076339
Journal: Geophysical Research Letters
Year of Publication: 2018
Volume: 44
Number: 24
Pages: 12,447-12,456
Date Published: 11/2018

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.

DOI: 10.1002/2017gl076339
Citation:
Frey, W, E Maroon, A Pendergrass, and J Kay.  2018.  "Do Southern Ocean Cloud Feedbacks Matter for 21st-Century Warming?"  Geophysical Research Letters 44(24): 12447-12456.  https://doi.org/10.1002/2017gl076339.