Ice melting at unprecedented rate
Massive MOSAiC sea ice research expedition records dramatic reduction of Arctic sea ice levels
Photo: Lianna Nixon / Alfred Wegener Institute
Researchers from Alfred Wegener institute Polarstern (Pole Star) research icebreaker inspect the floe.
MARIT FOSSE
Geneva
In a press briefing in Geneva on Sept. 22, Clare Nullis of the World Meteorological Organization (WMO) gave a grim picture of the situation in the Arctic. She said that the Arctic sea ice has reached its annual minimum extent after the summer melt season, and it was the second lowest extent only after the record low observed in 2012.
On Sept. 15, the U.S. National Snow and Ice Data Center (NSIDC) announced that the sea ice extent was 1.44 million square miles. The Alfred Wegener Institute confirmed this reading, with figures from the University of Bremen in Germany, saying it was 1.47 million square miles. The 2020 figure—still preliminary because a late-season surge of summer warmth could drop the extent further—continued an observed trend of long-term Arctic sea ice decline.
“It’s been a crazy year up north, with sea ice at a near-record low, 100-degree Fahrenheit 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 toward a seasonally ice-free Arctic Ocean, and this year is another nail in the coffin.”
“This threshold means the Arctic is more ocean than ice, a blue highway that’s been open since mid-July and won’t close until well into October,” said Ted Scambos, senior research scientist at the Earth Science Observation Center at the University of Colorado-Boulder.
There are a number of causes for the massive loss of ice this summer: Firstly, during the previous winter, primarily thin sea ice was formed in Russia’s marginal seas and soon melted again when the spring came. Secondly, this year the Arctic has seen extremely high air and water temperatures. Accordingly, heat impacted the ice from both above and below, resulting in widespread melting.
This summer, the rapid melting was observed in detail by experts on board the German research icebreaker Polarstern, which is the central observatory for the MOSAiC study, the most ambitious Arctic research expedition ever undertaken, involving scientists from 20 nations, including numerous researchers from Norway.
“The scale of Arctic sea-ice retreat this year was breathtaking. Just a short time ago, when we reached the North Pole, we could see broad stretches of open water reaching nearly to the Pole, surrounded by ice that was riddled with holes produced by massive melting. The Arctic ice is disappearing at a dramatic rate. With the MOSAiC expedition, we’re investigating the underlying processes on site, and in more detail than ever before, so that we can accurately represent these rapid changes in the Arctic in our climate models,” says Expedition Leader Professor Markus Rex.
Polarstern crossed the Geographic North Pole on Aug. 19, passing through the Fram Strait on the northeast side of Greenland in a region that used to be home to thick multi-year ice.
Among long-time observers of Arctic sea ice, the 2020 value was significant in that it not only punctuated a long-term decline, but also because it fell below the 1.5-million-square-mile threshold for only the second time in the satellite record. The first was in 2012, when the minimum extent dipped to 1.31 million square miles.
The exact time at which the sea ice reaches its absolute minimum depends on the weather conditions in the Arctic and can only be determined once there is clear evidence that the sea-ice extent has begun to grow again. Based on past experience, this usually comes in mid-September, though sometimes not until the second half of the month.
The sea ice extent is measured by satellite data, including by NASA and the NSIDC at the University of Colorado-Boulder. NSIDC defines extent as the area where ice concentration is at least 15 percent.
The low sea ice minimum in September 2020 followed a record-breaking heat wave and unprecedented wildfires in Siberia.
This article originally appeared in the Oct. 9, 2020, issue of The Norwegian American. To subscribe, visit SUBSCRIBE or call us at (206) 784-4617.
