Future Arctic sea-ice loss reduces severity of cold air outbreaks in midlatitudes
Screen, James A.
Geophysical Research Letters
American Geophysical Union (AGU)
©2016. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
The effects of Arctic sea-ice loss on cold air outbreaks (CAOs) in midlatitudes remains unclear. Previous studies have defined CAOs relative to present-day climate, but changes in CAOs, defined in such a way, may reflect changes in mean climate and not in weather variability, and society is more sensitive to the latter. Here we revisit this topic but applying changing temperature thresholds relating to climate conditions of the time. CAOs do not change in frequency or duration in response to projected sea-ice loss. However, they become less severe, mainly due to advection of warmed polar air, since the dynamics associated with the occurrence of CAOs are largely not affected. CAOs weaken even in midlatitude regions where the winter-mean temperature decreases in response to Arctic sea-ice loss. These results are robustly simulated by two atmospheric models prescribed with differing future sea ice states and in transient runs where external forcings are included.
This work was supported by the Natural Environment Research Council grants NE/M006123/1 and NE/J019585/1. The authors kindly thank Clara Deser, Lantao Sun and Bob Tomas for their efforts in performing the CAM4 simulations and for sharing these. We also thank Dr. Michael Kelleher for his aid with the code. The HadGAM2 simulations were performed on the ARCHER UK National Supercomputing Service. We acknowledge the World Climate Research Programme's Working Group on Coupled Modelling, which is responsible for CMIP5, and we thank the climate modeling groups for producing and making available their model output. Data from CMIP5 runs can be accessed through http://cmip-pcmdi.llnl.gov/cmip5/ and data from the sea ice experiments are available from the authors upon request.
This is the final version of the article. Available from American Geophysical Union (AGU) via the DOI in this record.
Published online 7 March 2016