Sea ice hits record low, but warming may not be to blame
Sea ice in Antarctica recently reached its lowest concentration on record, falling below 2 million square kilometres for the first time in 43 years of satellite observations.
In Antarctica, sea ice typically reaches its maximum coverage at the end of the southern winter in mid- to late September, and melts to its minimum extent in February.
The 2021-22 melt-and-freeze cycle has been a bit unusual, however. Sea ice reached its maximum extent on September 1, 2021, almost a month earlier than normal. The extent, measuring 18.75 million sq km, was also well above average. But it didn’t last long.
Sea ice retreated rapidly during spring and summer. In January and February, it cleared out from the Ross, Amundsen and northwest Weddell Sea regions.
According to the United States National Snow and Ice Data Centre (NSIDC), sea ice reached its minimum extent of 1.92 million sq km on February 25. The previous low – 2.11 million sq km – occurred in 2017.
Walt Meier, a research scientist at NSIDC, said the yearly fluctuations could be partly explained by geography. ‘‘The Antarctic is open to the ocean, so it’s very susceptible to changes and circulation changes in the ocean currents.’’
This year’s low concentration was likely in part to a long, strong low-pressure system that formed in late 2021 near the inner peninsula area, which created winds and warm air that helped to quickly erode ice in those areas.
Strong winds pushed ice from the Ross Sea into warmer waters farther north. At the same time, some areas experienced slightly higher concentrations of ice.
Despite the new low, scientists are cautious to attribute the low sea ice concentrations to climate change. In fact, research and data suggest that Antarctic sea ice concentrations have naturally fluctuated over the past 150 years.
Since 2016, sea ice concentrations have been on a slight downward trend. ‘‘If we see this going on for another five years, where we have record lows or near-record lows, then maybe we can start thinking about is it responding [to warming],’’ said Meier.
Both Antarctica and the Arctic are warming faster than the global average. Human-caused global warming has led to both the Antarctic and Greenland ice sheets to lose significant amounts of land ice.
This week, temperatures near the North Pole were about 28 degrees Celsius above normal, and temperatures in eastern Antarctica have catapulted up to 32C above normal amid a historically intense surge of warmth.