WASHINGTON — New satellite measurements show that crucial sea ice in the Arctic Ocean has plummeted to its second lowest level on record.

The National Snow and Ice Data Center in Boulder, Colo., announced Wednesday that the extent of sea ice in the Arctic is down to 2.03 million square miles. The lowest point on record is 1.65 million square miles set last September. With about three weeks left in the melt season, the record may fall, scientists say.

Arctic ice always melts in summer and refreezes in winter. But over the years, more and more of the ice is lost to the sea and not recovered in winter. That's important because the Arctic acts as a refrigerator for the globe.