Why has no new record-minimum Arctic sea-ice extent occurred since September 2012?

One of the clearest indicators of human-caused climate change is the rapid decline in Arctic sea ice. The summer minimum coverage is now approximately half of its extent only 40 yr ago. Four records in the minimum extent were broken since 2000, the most recent occurring in September 2012. No new rec...

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Bibliographic Details
Published in:Environmental Research Letters
Main Authors: Jennifer A Francis, Bingyi Wu
Format: Article in Journal/Newspaper
Language:English
Published: IOP Publishing 2020
Subjects:
Q
Online Access:https://doi.org/10.1088/1748-9326/abc047
https://doaj.org/article/2b0a4d9585cc4d7ca6d987f9ee0c33cb
Description
Summary:One of the clearest indicators of human-caused climate change is the rapid decline in Arctic sea ice. The summer minimum coverage is now approximately half of its extent only 40 yr ago. Four records in the minimum extent were broken since 2000, the most recent occurring in September 2012. No new records have been set since then, however, owing to an abrupt atmospheric shift during each August/early-September that brought low sea-level pressure, cloudiness, and unfavorable wind conditions for ice reduction. While random variability could be the cause, we identify a recently increased prevalence of a characteristic large-scale atmospheric pattern over the northern hemisphere. This pattern is associated not only with anomalously low pressure over the Arctic during summer, but also with frequent heatwaves over East Asia, Scandinavia, and northern North America, as well as the tendency for a split jet stream over the continents. This jet-stream configuration has been identified as favoring extreme summer weather events in northern mid-latitudes. We propose a mechanism linking these features with diminishing spring snow cover on northern-hemisphere continents that acts as a negative feedback on the loss of Arctic sea ice during summer.