The Arctic sea-ice cover peaked at 14.48 million square kilometers this year, making it the second-lowest maximum on record, according to scientists at NASA. Sea ice in the Arctic grew to its annual maximum extent on March 17, at about 60,000 square kilometers larger than the record low maximum reached on March 7, 2017.
"The Arctic sea ice cover continues to be in a decreasing trend and this is connected to the ongoing warming of the Arctic," said Claire Parkinson, a senior climate scientist at NASA's Goddard Space Flight Center in the US. "It's a two-way street: the warming means less ice is going to form and more ice is going to melt, but also, because there's less ice, less of the sun's incident solar radiation is reflected off, and this contributes to the warming, said Parkinson.
More significantly from a scientific perspective, the last four years reached nearly equally low maximum extents and continued the decades-long trend of diminishing sea ice in the Arctic. According to an analysis by NASA-supported National Snow and Ice Data Center (NSIDC) and NASA, this year's maximum extent was 1.16 million square kilometers below 1981 to 2010 average maximum extent.
According to NASA, every year, the sea ice cover blanketing the Arctic Ocean and surrounding seas thickens and expands during the fall and winter, reaching its maximum yearly extent sometime between late February and early April.
The NASA P-3 fueling up for its first science flight of the campaign.
Image credits: NASA/Jeremy Harbeck
The ice then thins and shrinks during the spring and summer until it reaches its annual minimum extent in September. Arctic sea ice has been declining both during the growing and melting seasons in recent decades, the US space agency said.
The decline of the Arctic sea ice cover has myriad effects, from changes in climate and weather patterns to impacts on the plants and animals dependent on the ice, and to the indigenous human communities that rely on them. The disappearing ice is also altering shipping routes, increasing coastal erosion and affecting ocean circulation, NASA noted.
The Arctic has gone through repeated warm episodes this winter, with temperatures climbing more than 40 degrees above average in some regions. The North Pole even experienced temperatures above the freezing point for a few days in February, NASA said. In mid-March, cooler temperatures and winds pushed out the edge of the sea ice pack and caused a late surge in ice growth that brought the maximum extent closer in line with the past few years.
Despite the fact that this year’s melt season will begin with a low winter sea ice extent, this doesn’t necessarily mean that we will see another record low summertime extent. “A lot will depend on what the wind and temperature conditions will be in the spring and summer,” Parkinson said.
Starting March 22, Operation IceBridge, NASA’s aerial survey of polar ice, is flying over the Arctic Ocean to map the distribution and thickness of sea ice. In the fall, NASA will launch a new satellite mission, the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2), which will continuously monitor how sea ice thickness is changing across the Arctic.
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