One of the reasons that Arctic sea ice has been disappearing over the past decades is that warm water from the Atlantic is being advected into the high-latitude ocean in increasing amounts. The process is called “atlantification.”
Key points
- New research by an international team of scientists explains what’s behind a stalled trend in Arctic Ocean sea ice loss since 2007.
- The findings indicate that stronger declines in sea ice will occur when an atmospheric feature known as the Arctic dipole reverses itself in its recurring cycle. The Arctic Dipole causes atmospheric wind patterns that modulate North Atlantic inflows across the Fram Strait and within the Barents Sea, resulting in variations in Arctic Ocean circulation, freshwater fluxes into the Amerasian Basin, ocean stratification, and heat fluxes.
- From 2007 to 2021, winds over North America and Eurasia were circulating in such a way that they reduced the influx of warmer Atlantic water into the Arctic.
- That helped slow the rate of sea ice loss during that time period — even as atmospheric warming ramped up . But that grace period may come to an end within just a few years.
- When the winds shift back, enhanced “Atlantification” of the Arctic may speed up sea ice loss, by giving an extra oomph of warming from below.
- The Arctic Dipole is a smaller-scale, regional pattern of winds that is having a global impact.
- From 1979 to 2006, the Arctic Dipole was in a “negative” phase, with winds rotating counterclockwise over North America and clockwise over Eurasia. That brought more Atlantic water into the Arctic via the Fram Strait, a narrow strip of ocean between Greenland and Norway’s Svalbard archipelago.
- During that time period, summertime sea ice extent shrank rapidly from year to year, vanishing at a rate of about 1 million square kilometers per decade.
- The year 2007, a record-breaking year for Arctic sea ice loss, marked the end of this “negative” phase of the Arctic Dipole. From then until 2021, the rate of sea ice loss across the entire Arctic slowed, shrinking by only about 70,000 square kilometers per decade — largely due to atmospheric warming.
