The amount of sea ice surrounding Antarctica has reached its lowest level for the second year in a row. 

In February, Antarctic sea ice reached its annual minimum extent of 1.79 million square kilometres, which is roughly 40% less than the average between 1981 and 2010, according to the National Snow and Ice Data Centre (NSIDC).

This is the lowest maximum extent on record since satellite measurements began in 1979.

In Antarctica, summers and winters are flipped compared to the Northern Hemisphere. So, sea ice normally reaches its maximum extent in September, when sea ice covers around 18.5 million square kilometers.

At the end of February, the National Snow and Ice Data Center found that historically only around 2.5 million square km of this sea ice remained.

This is the second year in a row that the record for the minimum sea ice extent has been broken.

What is sea ice?

Sea ice is frozen seawater that forms in polar regions. It is different from icebergs, which are formed from glaciers and are made of freshwater.

It is formed at much lower temperatures of around minus 1.8 degrees Celsius. 

Sea ice plays a crucial role in regulating the Earth’s climate and supporting Arctic and Antarctic ecosystems.

Scientists aren’t sure if this downward trend is likely to continue but this year’s measurement is the fifth lowest in the 45-year satellite record.

Last year, the minimum sea ice extent was less than 2 million square km, the lowest total since scientists began recording sea ice extent with satellites in 1979.

This can be blamed on the extraordinarily hot January, which was the seventh warmest on record, according to the National Oceanic and Atmospheric Administration.

‘By the end of January, we could tell it was only a matter of time [until the record was broken],’ Will Hobbs, an Antarctic sea ice expert at the University of Tasmania and the Australian Antarctic Program Partnership, told The Guardian.

Sea ice is a vital component of the Earth’s climate system, as it helps regulate the planet’s temperature by reflecting sunlight back into space.

It also supports a diverse array of Antarctic wildlife, including krill, penguins, and seals. Krill, in particular, are a keystone species in the Antarctic food web and serve as a vital food source for larger predators.

‘Lower sea ice extent means that ocean waves will pound the coast of the giant ice sheet, further reducing ice shelves around Antarctica,’ Ted Scambos, a senior research scientist at the Cooperative Institute for Research in Environmental Sciences, said in a statement.

The decline in sea ice extent is also linked to the warming of the polar regions caused by climate change. Warmer temperatures lead to more melting of sea ice in the summer and less formation of new sea ice in the winter.

In addition to sea ice extent, scientists are closely monitoring the Thwaites Glacier, also known as the ‘Doomsday Glacier’. The glacier is currently responsible for around 4% of global sea level rise, but its melting could accelerate and cause sea levels to rise by up to 2.4 meters if it were to completely collapse.

‘If these glaciers begin a more rapid runaway loss of land ice, it could trigger a dramatic increase in sea level rise rates before the end of this century,’ Julienne Stroeve, an NSIDC senior research scientist, said in the statement.

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