Yet more evidence that the Arctic is unravelling quickly due to human caused climate change. The National Snow and Ice Data Center, finds that while the amount of old (thickest) sea ice remained unchanged between March 2016 and March 2017, its movement over the past year suggest that currents will push it from the Arctic ocean and into the Atlantic ocean sometime this summer.
NASA explains why sea ice plays a critical role in the stability of our climate.
The area of the Arctic Ocean that is covered by sea ice increases during the winter and decreases during the summer. Data-maps from NASA satellites tell us that over at least the past 30 years, the area covered by Arctic sea ice has declined dramatically, with the most extreme decline seen in the summer melt season. Arctic sea ice is important because it reflects sunlight, keeping the polar regions cool and thereby moderating global climate.
The sea ice in the arctic moves continually. East of Greenland, the Fram Strait is an exit ramp for ice drifting out of the Arctic Ocean. Ice loss through the Fram Strait used to be offset by ice growth in the Beaufort Gyre, northeast of Alaska, where perennial ice could persist for years.
But around the start of the 21st century, the Beaufort Gyre became less friendly to perennial ice. Warmer waters made it less likely that ice would survive its passage through the southernmost part of the gyre. By around 2008, the very oldest ice had shrunk to a narrow band along the Canadian Arctic Archipelago.
In 1985, 16% of the ice pack (relative to the total sea ice areal coverage) was four years old and older, but by March 2016 old ice only constituted 1.2% of the ice pack. First-year ice now dominates the ice cover, comprising about 78% of the March 2016 ice pack, compared to about 55% in the 1980s.
The NSIDC reveals the findings on the grim news regarding the fate of the Arctic’s thickest ice this coming summer.
At the end of March, ice age data show only a small remaining coverage of old (5+ years) ice. Since 2011, the oldest ice has comprised less than 5 percent of the total ice cover. During the mid-1980s, such ice made up nearly a third of the ice.
The next oldest ice category, four-year-old ice has also dropped from about 8 to 10 percent to less than 5 percent. The coverage of intermediate age ice categories (2- and 3-year-old ice) has stayed fairly consistent through time. The oldest ice has essentially been replaced by first-year ice (ice that has formed since the previous September). First-year-ice has risen from 35 to 40 percent of the Arctic Ocean’s ice cover during the mid-1980s to about 70 percent now.
Comparison of March 2016 conditions to this year shows a similar percentage coverage for the different ice ages. However, the spatial distribution is different. In March 2016, bands of the oldest ice extended through the Beaufort Sea and into the Chukchi, with scattered patches north of the Canadian Archipelago and Greenland. This year, the oldest ice is consolidated against the coast of Greenland and the archipelago except for a short arm extending north to the region around the pole. Most of the third year ice is between Fram Strait and the pole, which means it is likely to exit the Arctic Ocean during the coming months.
x xYouTube VideoLink to NASA’s Goddard Space Flight Center for additional information.