Wind and its direction have significant influence over the sea ice as it decides where the warm waters of the Atlantic Ocean go
Annually changing wind patterns significantly influence the destiny of Arctic sea ice, controlling the amount of warm and salty Atlantic Ocean water flowing northward into the Arctic Ocean.
Between 2007 and 2021, the circulation of winds over North America and Eurasia reduced the inflow of warm Atlantic water to the Arctic. Thanks to this, ice melting slowed slightly during this time, despite atmospheric warming. This was reported by researchers in the new Science article. But this period is coming to an end. In the coming years, it is expected that the wind direction will reverse, which will give an additional impetus to ice melting. This process is called “Atlantification” of the Arctic.
There are many different regional and global patterns in the layers of the Earth's ocean and atmosphere. These regional and global patterns change from one phase to another over time. For example, the El Niño and La Niña phases of the El Niño Southern Oscillation.
According to Polyakov and his colleagues, the Arctic Dipole, being a regional pattern of winds, nevertheless has a global impact. In order to assess its influence, the scientists compared atmospheric wind patterns since 1979. The thickness and extent of summer ice were taken as indicators. To conduct the study, Satellite images, as well as airplane and shipboard surveys were studied. The conclusion that there is a clear relationship was made.
From 1979 to 2006, the Arctic dipole was in the "negative" phase. At that time, winds rotated counterclockwise over North America and clockwise over Eurasia. Thus, more Atlantic water was entering the Arctic through the Fram Strait. As a result of this wind pattern, the amount of summer ice was rapidly decreasing. The melting rate was about 1 million square kilometers per decade.
The "negative phase" of the Arctic dipole ended in 2007, the year in which the greatest amount of sea ice was lost. From 2007 to 2021, ice melt has declined markedly, reaching a rate of 70,000 square kilometers per decade. The melting was mostly due to atmospheric warming.
This does not give the right to say that the ice has recovered during this period. Its quantity is much lower than historical figures. However, the current "positive" phase of the Arctic dipole is helping to significantly slow the process and rate of sea ice loss in the Arctic. At the moment, the Arctic Ocean receives less warm Atlantic water from the Fram Strait. Now the less dense, colder, and fresh Arctic waters are on top of the warmer Atlantic waters. According to Thomas Rippeth, a physical oceanographer at Bangor University in Wales, that’s been protecting the sea ice from melting from below.
Since we are at the end of the “positive phase”, according to the study, this defense against glacial melt could disappear.
"We are beyond the peak of the currently positive Arctic dipole regime, and at any moment it could switch back again," Polyakov said. "This could have significant climatological repercussions, including a potentially faster pace of sea-ice loss across the entire Arctic and sub-Arctic climate systems."