«Everyone should be concerned»
Scientists are sounding the alarm: Antarctic sea ice is at its lowest level on record. With enough ice on the southernmost continent to raise sea levels by many meters if it melts, polar explorers are trying to find answers on how to avoid global cataclysms.
< span class="article__picture-author" itemprop="author">Photo: Global Look Press
For 44 years, satellites have helped scientists keep track of how much ice is floating in the ocean around Antarctica's 18,000-kilometer coastline. Every year, massive shifts occur in the coastal waters of the continent: in September, the sea ice extent reaches a maximum of about 18 million square meters. km, and by February drops to just over 2 million square meters. km.
But in all these four decades of satellite observations, there has never been less ice on the continent than was recorded last week.
“By the end of January, we could say that it was only a matter of time. It didn't even come close,” says Dr. Will Hobbs, an Antarctic sea ice expert at the University of Tasmania in partnership with the Australian Antarctic Program. “We see less ice everywhere. This is a circumpolar event.”
In the summer of 2022, in the southern hemisphere, the amount of sea ice on February 25 decreased to 1.92 million square meters. km, a record low based on satellite observations that began in 1979.
But by February 12 of this year, the 2022 record had already been broken. The ice continued to melt, hitting a new record low of 1.79 million square feet on February 25. km and breaking the previous record by 136,000 sq. km — an area twice the area of u200bu200bthe island of Tasmania.
In the spring, in the southern hemisphere, strong winds over western Antarctica ruffled the ice. At the same time, Hobbs says that large areas in the west of the continent have barely recovered from the losses of the previous year.
“Because the sea ice is so reflective, it is difficult to melt it from sunlight. But if there is open water behind it, it could melt the ice from below,” notes Dr. Hobbs.
Hobbs and other scientists said the new record — the third time it has been broken in six years — has started a scramble for answers among polar scientists.
The fate of Antarctica — especially ice on land — is important because the continent contains enough ice to raise sea levels many meters if it were to melt.
While melting sea ice does not directly raise sea levels because it is already floating on the water, several scientists told The Guardian about side effects that can.
Sea ice helps mitigate the impact of storms on the ice attached to the coast. If it starts to disappear for longer, increased wave action could weaken those floating ice shelves that themselves stabilize the massive ice sheets and glaciers behind them on land.
One of the main areas of concern is the marked loss of ice in the Amundsen and Bellingshausen Seas in the west of the continent. Although the average amount of sea ice around the continent had increased by 2014, there were losses in these two neighboring seas. This is important because the region is home to the vulnerable Thwaites Glacier, known as the “Doomsday Glacier” because it contains enough water to raise sea levels by half a meter.
“We don't want to lose sea ice where there are these vulnerable ice shelves and behind them ice sheets,” says Prof Matt England, an oceanographer and climate scientist at the University of New South Wales. “We are likely starting to see signs of significant warming and sea ice retreat [in Antarctica]. Seeing it reach these levels is definitely worrisome because we have these potentially reinforcing feedbacks.»
Data provided by scientists Dr. Rob Massom of the Australian Antarctic Division and Dr. Phil Reid of the Bureau of Meteorology, show that two-thirds of the continent's coastline was open to water last month — well above the long-term average of about 50%.
“It's not just about the area of ice, it's about the duration of coverage,” says Dr. Massom. “If you remove the sea ice, you expose the floating edges of the ice to waves that can bend them and increase the chance that these ice shelves will break away. This then allows more ground ice to enter the ocean.”
Rob Massom and Phil Reid published a study last year in which they found that since 1979, the Amundsen Sea has experienced longer ice-free periods and exposed much of the coastline to the open ocean.
Dr. Ted Scambos – a sea ice expert from the University of Colorado at Boulder who also works on Antarctic sea ice at the university's National Snow and Ice Data Center, the world's polar ice monitoring center. He said the shrinking sea ice in Antarctica “makes the scientific community wonder if there is a process associated with global climate change.”
Antarctica is difficult to study not only because of its remoteness, but also because of the problems of collecting data across the continent, subject to huge fluctuations in wind and storms from all directions.
Scambos noted: “Since 2016, there has been a rather sharp reduction in sea ice, and especially given that these record years in a row, as well as many months were near-record low, it makes the scientific community wonder if there is a process associated with global climate change.”
The expert emphasized that while the most recent record may be partly due to the La Niña climate system, which tends to bring warmer winds to the peninsula of the continent, this does not explain the losses in other areas.
“We still trying to figure out what has changed now,” he says. “But it is clear that shrinking sea ice will have an impact. This will affect the continental ice because most of the coast will be exposed.”
For years, Antarctica seemed to confuse some climate models as sea ice — on average — increased slightly before the catastrophe in 2016.
Dr. Ariaan Puric, a climate scientist at Monash University, studies why the sea ice did not behave as some expected. She said it was probably caused by changing winds and, contrary to common sense, meltwater from the land entering the ocean, which made it easier for the ice to form.
One study found that ocean warming also contributed to the sudden drop in sea ice in 2016. “All models assume that as the climate warms, we expect Antarctic sea ice to shrink,” she says. There is a widespread consensus on this. So this low sea ice level is consistent with what the climate models show.”
Antarctic scientists are now struggling to figure out what's going on. Are melting sea ice and successive record lows just a natural phenomenon on a continent notoriously difficult to study? Or are these records just another clear sign that a climate crisis is hitting a frozen continent?
“Antarctica may seem remote, but changes around it could affect the global climate, and melting ice sheets are affecting coastal communities across around the world, says Dr. Puric. “Everyone should be concerned about what is happening in Antarctica.”