Arctic sea ice thins in 2 big jumps and becomes more vulnerable

According to a new study, climate change has attacked the crucial thickness of the Arctic sea ice in two sudden big sinkholes instead of a steady nibble.

Just over 15 years ago sea ice was rapidly losing more than half its thickness, becoming weaker, more likely to melt and less likely to recover, according to the study which highlights the importance of two major ” regime changes” that changed the complexion of the Arctic.

These big bites happened in 2005 and 2007. Prior to that, the Arctic sea ice was older and deformed in a way that made it difficult to move out of the region. This has helped the polar zone act as the globe’s air conditioner even during the hottest summers. But now the ice is thinner, younger and easier to expel from the Arctic, putting this crucial cooling system at risk, the study’s lead author said.

Before 2007, 19% of sea ice in the Arctic was at least 13 feet thick (4 meters) – larger than most elephants – but now only around 9.3% of the ice is at least as thick thick. And the age of the ice has fallen by more than a third, from an average of 4.3 years to 2.7 years, according to the study published Wednesday in the journal Nature.

He cited “the lasting impact of climate change on Arctic sea ice”.

“The ice is much more vulnerable than before because it’s thinner, it can easily melt,” said study lead author Hiroshi Sumata, a sea ice scientist at the Norwegian Polar Institute. Thicker sea ice is crucial for all kinds of life in the Arctic, he said.

The study shows “how the Arctic sea ice environment has undergone a fundamental change,” said Walt Meier, a scientist at the National Snow and Ice Data Center, who was not part of the research. “This article helps explain why the sea ice has not recovered from these large falls.”

Previous studies have focused more on the extent of Arctic sea ice, or its extent, as it is easily measured by satellites, which do not observe volume well. But 90% of sea ice is eventually pushed out of the Arctic through the Fram Strait by Greenland, so Sumata overcame the challenges of measuring from space by focusing its observations on this ground-based choke point. .

He found that the first ice was getting younger, making it thinner and more uniform, and easier to push through Fram Strait. Thicker ice has all sorts of weird edges and shapes that make it harder to get out of the Arctic due to aerodynamics, but smoother, younger ice doesn’t, Sumata said. .

Scientists previously knew that sea ice was shrinking and thinning, but this “flushing” is essential, said Mark Serreze, director of the National Snow and Ice Data Center, who was not part of the study.

‚ÄúSuch flushing episodes have reduced the residence time of ice in the Arctic Ocean by more than a year, so it has less time to thicken and it is the thick ice that resists melting. “Serreze said in an email. “But since the Arctic is warming rapidly, we’re probably past the point of hoping the Arctic Ocean can recover.”

What likely happened in 2005 and 2007 were periods of warm, widespread, ice-free open water in the Arctic that exceeded periods of previous summers, Sumata said. The white ice reflects the sun’s rays, but the dark ocean absorbs them and heats up – what’s known as ice albedo feedback. This warmer water cycle has made it harder for ice to form, survive and thicken, he said.

Once the ocean accumulates this heat, it cannot easily return. So in the future, larger, warmer changes may occur to make the ice thinner and weaker, but don’t count on sudden, healing cooling changes, the scientists said.

Sumata and Serreze think these sudden hot jumps will happen soon and are surprised they haven’t quite happened yet. According to recent projections, the Arctic Ocean will be ice-free for parts of the summer in 20 to 30 years.

Sea ice thickness and the overall health of the Arctic are crucial, even in areas thousands of miles away that don’t freeze over, Sumata said.

“It will affect the whole Earth because the north and south poles are something like the Earth’s radiator, the Earth’s air conditioning system,” Sumata said. “And the situation we observed indicates that the air conditioner is not working well.”


Follow AP’s climate and environment coverage at


Follow Seth Borenstein on Twitter at @borenbears


The Associated Press’s climate and environmental coverage receives support from several private foundations. Learn more about AP’s climate initiative here. The AP is solely responsible for all content.

Leave a Comment