Scientists with the National Snow and Ice Data Center (NSIDC) in the U.S. state of Colorado said Wednesday that, as summer was ending in the Northern Hemisphere, Arctic sea ice had shrunk less in 2021 than in other recent years.
Supported by NASA and other federal agencies, the NSIDC is part of the Cooperative Institute for Research in Environmental Sciences at the University of Colorado in Boulder. It is among the research organizations that monitor the ebb and flow of the Arctic ice pack. Scientists with the center determined the ice pack reached its minimum extent for the year on September 16.
Sea ice extent is defined as the total area in which ice concentration is at least 15%
This year, satellite observations determined Arctic ice covered a minimum of 1.82 million square kilometers, which NSIDC scientists said was the highest minimum coverage since 2014, and the 12th lowest in 43 years of satellite records.
In a statement, NSIDC Director Mark Serreze said, “We had a reprieve this year — a cool and stormy summer with less ice melt. But the amount of old, thick sea ice is as low as it has ever been in our satellite record.”
The NSIDC said the last 15 years have produced the lowest 15 sea ice extents in the satellite record. The amount of old, multiyear ice — that is, ice that has remained frozen through at least one summer melt season — is at one of the lowest levels in the ice age record, which began in 1984.
The center cautioned the Arctic Sea ice extent figures were preliminary, as continued melting could still push the ice minimum extent lower before the early winter freeze begins. NSIDC will issue a formal announcement at the beginning of October with full analysis of the possible causes behind this year’s ice conditions.