Arctic Sea Ice Ties For Seventh-Lowest Maximum

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The Arctic sea ice appeared to have reached its likely maximum extent for the year on March 13, according to the National Snow & Ice Data Center, and in doing so tied for the seventh-lowest in the 40-year satellite record.

The United States’ National Snow & Ice Data Center (NSIDC), part of the University of Colorado Boulder Cooperative Institute for Research in Environmental Sciences (CIRES), monitors Arctic and Antarctic sea ice in near real-time and is one of the world’s leading authorities on the history and science of how climate change is impacting our planet’s icy poles.

According to NSIDC’s most recent update, published on Wednesday, Arctic sea ice appears to have reached its annual maximum extent on March 13 at 14.78 million square kilometers (5.71 million square miles). The “maximum extent” of the Arctic’s and Antarctic’s sea ice refers to the area of ocean where there is at least some sea ice, measured therefore in square kilometres (and not an as-the-crow-flies measurement from some arbitrary middle). “Usually, scientists define a threshold of minimum concentration to mark the ice edge; the most common cutoff is at 15%,” explains NSIDC. “Scientists use the 15% cutoff because it provides the most consistent agreement between satellite and ground observations.”

This is the seventh-lowest maximum in the 40-year satellite record, tying with 2007’s maximum extent, and 860,000 square kilometers (332,000 square miles) below the 1981-2010 average maximum of 15.64 million square kilometers (6.04 million square miles) and 370,000 square kilometers (143,000 square miles) above the lowest maximum of 14.41 million square kilometers (5.56 million square miles) set on March 7, 2017.

Ten lowest maximum Arctic sea ice extents (satellite record, 1979 to present)

Rank	In millions of square kilometers	In millions of square miles
5.77 5.78	March 12 March 21

It is worth noting that at the moment, this is a preliminary assessment pending a final analysis which will be conducted at the beginning of April by NSIDC scientists.