Siberian Heat Wave Shrinks Arctic Sea Ice To Second-Lowest Level Ever Recorded

The Arctic Ocean's floating ice cover shrank this year to its second-lowest extent since modern recording began nearly four decades ago, driven in part by the impact of a Siberian heat wave.

The Arctic sea ice cover shriveled to 3.74 million square kilometers by September 15, according to satellite data by U.S. space agency NASA and the National Snow and Ice Data Center (NSIDC) at the University of Colorado Boulder released on September 21.

“It's been a crazy year up north, with sea ice at a near-record low, 100-degree Fahrenheit (38 degrees Celsius) heat waves in Siberia, and massive forest fires,” said Mark Serreze, director of NSIDC.

“The year 2020 will stand as an exclamation point on the downward trend in Arctic sea ice extent. We are headed towards a seasonally ice-free Arctic Ocean, and this year is another nail in the coffin.”

This year's melt is second only to 2012, when the ice cover shrank to 3.4 million square kilometers, according to NSIDC, which has been keeping satellite records since 1979. In the 1980s, the ice cover was about 2.7 million square kilometers bigger than current summer levels -- an area equivalent to Kazakhstan.

Polar sea ice undergoes seasonal patterns of change -- thickening and expanding to cover the entire Arctic Ocean and neighboring seas in winter, then thinning and shrinking in the spring and summer before reaching a low point in mid-September.

Scientists say a Siberian heat wave in the spring and summer, as well as natural Arctic climate phenomenon and warming caused by greenhouse gases, contributed to the polar sea melt.

Temperatures in the Siberian Arctic for much of the year were 8 to 10 degrees Celsius above normal.

Scientists say abnormal temperature increases and wildfires in the Siberian Arctic are worrying because it can thaw permafrost and release climate-warming methane from the frozen land.

There are also cascading effects causing Arctic sea ice melt.

Thin ice from previous warm years melts quicker than thicker ice, creating a negative feedback mechanism. Sea ice removal also exposes ocean, which absorbs more sun radiation and heat than reflective ice and contributes to a faster melt.

“As the sea ice cover extent declines, what we’re seeing is we’re continuing to lose that multiyear ice,” Serreze said. “The ice is shrinking in the summer, but it’s also getting thinner. You’re losing extent, and you’re losing the thick ice as well. It’s a double whammy.”

There have also been warmer air temperatures, which have risen twice as fast in the Arctic as for the planet as a whole. In addition, scientists say warmer water from the Atlantic Ocean is moving closer to the bottom of the sea ice and warming it from below.

While melting sea ice does not increase ocean levels, the same summertime warning of Arctic waters diminishes ice sheets covering Arctic lands in Canada, Russia, and Greenland.

The faster those ice sheets melt into the ocean, the faster global sea levels will rise.

With reporting by AFP, AP, and Reuters