Sea ice around Antarctica shrinks to record low

The continent of Antarctica is surrounded by sea ice. The amount of ice grows in the winter and shrinks in summer. The total area is covers changes from year to year. And it just set a new record in January, the National Oceanic and Atmospheric Administration reports. That month, Antarctic sea ice shrunk to the lowest monthly extent ever recorded.

Antarctic sea ice averaged just 4.04 million square kilometers (1.6 million square miles). That’s 1.19 million square kilometers (0.46 million square miles) below the 1981 through 2010 average. And that’s 280,000 square kilometers (108,000 square miles) smaller than the previous record low, set in 2006.

The new record comes just two years after the largest January Antarctic sea ice extent on record. Southern Hemisphere sea ice had been growing by about 3 percent per decade since recordkeeping began in 1979. However, there is a lot of year-to-year variation.

The cause of the record-low ice — and whether future years will similarly buck the growing trend — is unclear, James Pope said in a statement. He is a climate scientist with the British Antarctic Survey in Cambridge, England. “It is difficult to identify what is causing the record minimum and whether anything significant has changed” so close to the record-setting event, he said. Researchers may not understand for years what caused the decline in sea ice. “We will now study the data with interest and look at what is causing this minimum,” he said.

Meanwhile, in the Northern Hemisphere, where it is winter, Arctic sea ice is growing. But sea ice there set another record. It had its smallest January extent on record. That edges out the previous record — set just last year.