Antarctic sea ice has reached record low levels for the second time in two years, with some scientists alarmed that dramatic drops are a signal the climate crisis may now be more clearly influencing this vast, complex and isolated region.
The sea ice that fringes Antarctica dropped to just 737,000 square miles (1.91 million square kilometers) on February 13, according to the National Snow and Ice Data Center, or NSIDC, below the previous record of 741,000 square miles (1.92 million square kilometers) set on February 25 last year.
Sea ice could still shrink further; the lowest level of the southern summer may not be reached for more than a week.
The last two years mark the only time that sea ice levels have dipped below 2 million square miles since satellites began monitoring it in 1978.
It’s “not just ‘barely a record low,’” Ted Scambos, a glaciologist at the University of Colorado Boulder. “It’s on a very steep downward trend.”
Unlike the Arctic, where the rate of sea ice loss has followed a fairly consistent downward trajectory as climate change accelerates, Antarctic sea ice extent has swung up and down, making it harder to figure out how the continent and its surrounding ocean are responding to global heating.
The two polar regions are very different. While the Arctic is an ocean surrounded by continents, Antarctica is a continent surrounded by the ocean – this means its sea ice can grow outward, unconstrained by land. Antarctic ice tends to be thinner than Arctic ice, with greater highs in the winter and steeper declines in the summer.
Climate models projected declines in Antarctic sea ice that were similar to the Arctic, but until recently the region was behaving completely differently than those models predicted.
It hit a record high for winter sea ice extent in 2014 when it reached 7.76 million square miles, which seemed to support the idea that the Antarctic may be relatively insulated from global warming.
