New research finds that “unusual changes in atmospheric jet stream circulation caused the exceptional surface melt of the Greenland Ice Sheet (GrIS) in summer 2012.”
Prof. Jennifer Francis tells me these changes are consistent with those caused by warming-driven “Arctic Amplification.” And that means GrIS may melt faster than climate models have projected.
Extent of surface melt over Greenland’s ice sheet on July 8, 2012 (left) and July 12, 2012. In just a few days, the melting had dramatically accelerated and an estimated 97 percent of the ice sheet surface had thawed. Credit: NASA.
Back in May, a study found that by 2025, there is a “50-50 chance” of this unprecedented ice melt happening annually simply based on the continued rapid warming of GrIS.
This new study, “Atmospheric and oceanic climate forcing of the exceptional Greenland ice sheet surface melt in summer 2012,” suggests this kind of melt may become commonplace even sooner.
As the news release explains, an international team used a computer model and satellite data “to confirm a record surface melting of the GrIS for at least the last 50 years – when on 11 July 2012, more than 90 percent of the ice-sheet surface melted. This far exceeded the previous surface melt extent record of 52 percent in 2010.” Weather station data “showed that several new high Greenland temperature records were set in summer 2012.”
The research “clearly demonstrates that the record surface melting of the GrIS was mainly caused by highly unusual atmospheric circulation and jet stream changes, which were also responsible for last summer’s unusually wet weather in England.”
What were these changes? Professor Edward Hanna from the University of Sheffield’s Department of Geography explains: