Explained | Arctic sea ice peaked on February 25 this year. Why is that important?

Sea ice in the Arctic usually reaches its peak in March, this year the maximum extent was recorded on February 25.

The story so far: The Arctic winter sea ice hit its maximum extent on February 25 this year, according to the data collected by the United States National Snow and Ice Data Centre (NSIDC). This is the tenth-lowest in the satellite record maintained by the NSIDC, a Distributed Active Archive Centre of National Aeronautics and Space Administration (NASA).

Arctic sea ice extent peaked at 14.88 million square kilometres, according to the data analysed by the NSIDC. This is around 770,000 square kilometres below the 1981-2010 average maximum, equivalent to an area of ice slightly larger than the U.S. states of Texas and Maine combined.

Since February 25, the extent of Arctic sea ice has dropped around 390,000 square kilometres. The loss of sea ice has primarily been observed in the Sea of Okhotsk and the Barents Sea. The losses, however, have been offset by gains in the Bering Sea, Baffin Bay, and the Labrador Sea, according to NSIDC. At the same time, gains in the Antarctic sea ice are not enough to balance the loss in Arctic sea ice.

Sea ice is essentially frozen ocean water. All stages of winter sea ice – formation, growth, and melting – occur in the ocean, unlike icebergs, glaciers and ice shelves that originate on land.

Sea ice in the Arctic usually reaches its peak in March. The minimum extent is usually recorded in September after it melts through the warmer months. The Antarctic sea ice in the south follows the opposite cycle.

According to NASA, the maximum extents of the sea ice in the Arctic have declined at a pace of about 13% per decade since 1979 – when satellites began reliably tracking the data. This is in sync with human global warming activities like emission of carbon dioxide, deforestation, and so on.

Polar sea ice is important to maintain global temperatures.