The wintertime extent of sea ice for 2021 reached its maximum on March 21 after growing during the fall and winter. And space observations show that things are not looking good. The extent is the seventh lowest on record, tying with the year 2007 and the lowest it has been since 2018, which was number second on the list.
The extent of the sea ice was about 14.77 million square kilometers (5.70 million square miles). That’s 880,000 square kilometers (340,000 square miles) less than the median extent for the 1981 to 2010 period. That’s an area larger than Florida and Texas combined or 1.5 times the area of France.
The lowest ever wintertime extent was in 2017 when it reached 14.41 million square kilometers (5.56 million square miles). This dramatic reduction of the ice cover over the Arctic ocean is a direct consequence of anthropogenic global warming. Seven out of ten of the lowest wintertime extension have happened in the last decade. All ten have happened in the 21st century. The lowest four were from 2015 to 2018.
There are cycles of natural variability that affect the extent of the ice both in summer and in winter. The Arctic Oscillation, a pattern of sea-level pressure anomalies, is one of such cycles. But the natural phenomena present and combined cannot explain what is happening in the northernmost region of our planet. This huge environmental change is on us.
Satellite observations have been tracking the changes in sea ice since 1978. Since then, Arctic ice has decreased in all months and virtually in all regions of the Arctic circle. And the decline in Arctic sea ice is undeniable, with the rate of decline getting worse in this century.
For the summer extent, since 2002, the minimum has been consistently much smaller than the long-term average. Consider that by last October, an important region of the Siberian coast, the Laptev Sea has failed to freeze for the first time in history. This region is considered a sea ice nursery, so this event will have major consequences. Last summer had the second-smallest sea ice extent.
The reduction in summer ice matters as the Arctic is losing its multi-year ice. Most of the ice in the winter is brand new ice that has just formed. This makes the whole ice cap thinner and many researchers believe the Arctic will be ice-free during summer around 2030 and 2050.
The current observations were conducted by JAXA, the Japanese space agency, using their “SHIZUKU” (Global Change Observation Mission 1st-Water) satellite and the analysis and visualizations of the sea ice extent were created by a NASA team at the Goddard Space Flight Center.