Antarctica sea ice has fallen to an “alarming” level during the southern hemisphere summer, scientists have revealed.
The ice surrounding Earth’s southernmost continent now measures less than 772,200 square miles (2 million square kilometers), or about the size of Mexico.
Worryingly, this is the third year in a row that this figure has fallen below this threshold, according to the US National Snow and Ice Data Center (NSIDC).
Less sea ice can threaten the habitats of penguins, seals and other Antarctic animal species, and also contributes to global sea level rise.
Unfortunately, there is also a record low for Antarctic sea ice during the winter.
Antarctica’s “sea ice extent” refers to the ice surrounding the coast of Antarctica. Here, the average sea ice extent between 1981 and 2010 for this time of year is marked in orange, but in much of this area the ice is now “missing”
Sea ice plays an important role in maintaining the Earth’s energy balance while also helping to keep the polar regions cool due to its ability to reflect more sunlight back into space. Pictured is sea ice in the water off Cuverville Island in Antarctica.
Walt Meier, a research scientist at the NSIDC, said experts “still don’t know the full reason” why sea ice is now at a record level, although “global warming certainly could be a factor.”
“It appears that warm ocean temperatures are important, but other factors may be at play, including wind patterns,” he told MailOnline.
‘We only have 45 years of high-quality data, which may not yet reflect all the variability of Antarctic sea ice.
“However, since 2016, Antarctic sea ice has for the most part been much lower than normal, with record lows at times.”
Professor Martin Siegert, a glaciologist at the University of Exeter, agreed that “we don’t know for sure” what the cause is.
“It would be nice to have a definitive answer, but it doesn’t really matter much,” he told MailOnline.
“We certainly can’t afford to attribute it to variability as an excuse for not stopping the burning of fossil fuels; that would be crazy.”
Antarctica’s sea ice is vitally important because it reflects sunlight, which helps keep the polar regions cool.
Without this ice cover, dark areas of the ocean are exposed, absorbing sunlight instead of reflecting it, which in turn warms the region and further accelerates ice loss.
Climate scientists constantly track sea ice extent throughout the seasons and compare its size to the same months in previous years to see how it is changing. Data from the National Snow and Ice Data Center have recently shown that sea ice extent is below average since records began, regardless of the time of year.
According to the NSIDC, the five-day average sea ice cover fell to 768,343 square miles (1.99 million square kilometers) on February 18.
It then fell further to 764,482 square miles (1.98 million square kilometers) on February 21.
This is still not as severe as the record minimum ice extent set in February 2023 of 683,400 (1.77 million square kilometers).
However, if we look at the bigger picture, the three lowest years on record are the last three years, according to scientists.
Ice sheet surface melt on the Antarctic Peninsula slowed sharply in mid-January and remained low until February 15.
Because it is summer in the Southern Hemisphere, most of Antarctica’s ice is currently estimated to be only 3 to 6.5 feet (1 to 2 meters) thick.
Dr. Ariaan Purich, a climate scientist at Monash University in Australia, believes the ice is thinner than usual since it re-formed after the winter.
“It seems plausible, and thinner sea ice could melt more quickly,” Dr. Purich said. the Guardian.
Antarctica’s “sea ice extent” refers to the ice surrounding the coast of Antarctica and does not include ice covering the continental landmass.
Due to colder temperatures, sea ice reaches its maximum extent in the southern hemisphere winter (July to September).
But temperatures gradually rise and reach a minimum during the southern hemisphere summer (December to February).
As in the Arctic, the ocean surface around Antarctica freezes in winter and melts each summer. Antarctic sea ice (pictured) generally reaches its annual maximum extent in mid to late September (winter) and reaches its annual minimum in late February or early March (summer).
Climate scientists constantly track sea ice extent throughout the seasons and compare its size to the same months in previous years to see how it is changing.
So while there is great variability in ice extent depending on time of year, it is lower than the average since records began, regardless of the season.
Last year, during the southern winter, the NSIDC reported that Antarctic sea ice levels are at a “mind-blowing” record low for the time of year, at less than 6.5 million square miles (17 million square kilometers).
This is 580,000 square miles (1.5 million square kilometers) less than the September average and is equivalent to five times the size of the British Isles.
Ice melting in parts of Antarctica, including the Antarctic Peninsula, was also above average between mid-January and mid-February.
In a recent blog post, NSIDC also said that weather conditions from January 15 to February 15 continued to be warm in central West Antarctica, where air temperatures were 4°F (2°C) above average from 1991 to 2020.
Meanwhile, ice on the Antarctic Peninsula – the part of the continent that sticks out like a tail – fell sharply in mid-January and remained low until February 15.
Rapid warming has already caused a significant southward shift and contraction in the distribution of Antarctic krill, a keystone species, activists said.
A recent Greenpeace expedition to Antarctica also confirmed that gentoo penguins are breeding further south as a result of the climate crisis.