On 18 March, 2022, scientists at the Concordia research station on the east Antarctic plateau documented a remarkable event. They recorded the largest jump in temperature ever measured at a meteorological centre on Earth. According to their instruments, the region that day experienced a rise of 38.5C above its seasonal average: a world record.
This startling leap – in the coldest place on the planet – left polar researchers struggling for words to describe it. “It is simply mind-boggling,” said Prof Michael Meredith, science leader at the British Antarctic Survey. “In sub-zero temperatures such a massive leap is tolerable but if we had a 40C rise in the UK now that would take temperatures for a spring day to over 50C – and that would be deadly for the population.”
For the past two years scientists have been inundated with rising numbers of reports of disturbing meteorological anomalies on the continent. Glaciers bordering the west Antarctic ice-sheet are losing mass to the ocean at an increasing rate, while levels of sea ice, which float on the oceans around the continent, have plunged dramatically, having remained stable for more than a century.
These events have raised fears that the Antarctic, once thought to be too cold to experience the early impacts of global warming, is now succumbing dramatically and rapidly to the swelling levels of greenhouse gases that humans continue to pump into the atmosphere.
These dangers were highlighted by a team of scientists, led by Will Hobbs of the University of Tasmania, in a paper that was published last week in the Journal of Climate. After examining recent changes in sea ice coverage in Antarctica, the group concluded there had been an “abrupt critical transition” in the continent’s climate that could have repercussions for both local Antarctic ecosystems and the global climate system.
“The extreme lows in Antarctic sea ice have led researchers to suggest that a regime shift is under way in the Southern Ocean, and we found multiple lines of evidence that support such a shift to a new sea ice state,” said Hobbs.
The dramatic nature of this transformation was emphasised by Meredith. “Antarctic sea ice coverage actually increased slightly in the late 20th and early 21st century. However, in the middle of the last decade it fell off a cliff. It is a harbinger of the new ground with the Antarctic climate system, and that could be very troubling for the region and for the rest of the planet.”
If all the ice on Antarctica were to melt, this would raise sea levels around the globe by more than 60 metres. Islands and coastal zones where much of the world’s population now have homes would be inundated.
Such an apocalypse is unlikely to occur for some time, however. Antarctica’s ice sheet covers 14m square kilometres (about 5.4m square miles), roughly the area of the United States and Mexico combined, and contains about 30m cubic kilometres (7.2m cubic miles) of ice – about 60% of the world’s fresh water. This vast covering hides a mountain range that is nearly as high as the Alps, so it will take a very long time for that to melt completely, say scientists.
The crisis facing the continent has widespread implications. More than 40 nations are signatories of the Antarctic Treaty’s environmental protocol, which is supposed to shield it from a host of different threats, with habitat degradation being one of the most important. The fact that the continent is now undergoing alarming shifts in its ice covering, eco-systems and climate is a clear sign that this protection is no longer being provided.
