Amid the doomsday scenes triggered by extreme weather in Europe, Asia and North America, perhaps the most alarming global climate event occurs in Antarctica, where sea ice formation has reached an all-time low. The continent currently lacks an area of ice larger than Greenland.
“It’s not just a record, it’s a home run,” said Caroline Holmes, a polar climate scientist with the British Antarctic Survey.
While the depletion of sea ice in the Northern Hemisphere has been a worrisome marker of human impacts on the planet for decades (the lowest sea ice level measured in the Arctic was in 2012), in Antarctica a story has unfolded that, despite rising global average temperatures, Antarctic winters still produced massive amounts. However, in the past seven years, there has been a sharp reversal in the trend.
“If you look at a graph for a normal year, you would see this sharp increase in the amount of ice forming between February and November, particularly this time of year,” he adds.
“If you plot on an annual basis, you can see a tight group of lines that show how the sea ice grows each year. Then if you were to just look at 2022, you would see that it was at the bottom of those lines. It didn’t look like it stood out, but it was the shortest ever. If you add 2023, you can see that it is well below anything we have observed since we began these measurements in 1979.”
The figures reveal that the sea ice extent in July was 15 percent below the long-term average. Last year, already a record low, it was about 6 percent below the long-term average. More than two million square kilometers of ice have not frozen.
“If you averaged the extent of sea ice around the coast, it would extend about 1,000 kilometers from the coast, but this year the recordings mean it is about 100 kilometers further back than in a normal year,” Holmes says. .
single event
With modeled data going back 120 years, long before satellite technology, there is still no precedent for the low ice levels we see today. It is difficult to overstate the magnitude of the anomaly. Information collected since 1970 indicates that the probability of such a significant decline would be a once-in-7.5 million-year event.
However, Holmes cautions that the current data may still not be telling us enough about how sea ice extent may behave naturally. As a result, scientists cannot definitively point a finger at human-caused climate change, despite the strong indication that this is an important part of the picture.
The record low ice comes as average sea surface temperatures remain at a record low that began in May of this year. On August 1, ocean surface temperatures topped an all-time high of 20.96 degrees Celsius, well above average for the time of year and hotter than the previous record set in March 2016, according to the Climate Change Service. Copernicus of the European Union.
One obvious concern for humans is rising sea levels. If a pattern of strengthening loss occurs, this could have major ramifications for billions of people around the world. Sea ice may be a relatively thin layer, but it provides a considerable “buffering” effect on waves, protecting Antarctic ice shelves from more rapid disintegration and melting in rough seas.
glacier expanses
The ice shelves, which can rise up to 600 meters thick above the sea, are the floating extensions of glaciers on the Antarctic continent. Increased exposure to open water means that thick sheets of ice could break up more quickly.
Antarctica represents vast amounts of ice, about 90 percent of all that natural resource in the world, with the ultimate capacity to raise sea levels by about 70 meters if it all melted. However, the last time Antarctica was free of ice was at least 34 million years ago.
Continued loss of sea ice, experts say, could also cause the feedback loop to worsen, blocking further global warming. This is because the high reflectivity of a white, ice-covered surface reflects a considerable amount of the Sun’s energy back into space. Without ice, the dark energy-absorbing open ocean is exposed directly to sunlight, which in turn warms the ocean, further preventing ice formation.
The loss of sea ice could have devastating impacts in one of the most biodiverse regions in the world. Changes in their distribution will affect marine species by altering light levels in the ocean, how salinity and current changes move nutrients, and also as a habitat in its own right. Penguins and seals depend on it; In addition, it provides hunting grounds for other animals, such as orcas.
It is also a key resource for smaller organisms, such as plankton and krill, which play important roles in the food chain. “We know that seabirds such as albatrosses and seals, particularly fur seals, have population cycles with good years and bad years, which is related to the availability of krill,” adds Katrin Linse, senior biodiversity biologist. from the British Antarctic Survey.
“Whales feed on it and you have patches with hundreds of millions of krill swimming around. The biomass of it is only slightly less than the biomass of humans on Earth.”
He adds: “biodiversity (in Antarctica) is complex. “We are talking about 700 pelagic species (those that inhabit the open ocean), 8,500 described benthic (seabed) and another 8,000 that live in the Southern Ocean.”
© The Independent
Translation: Juan José Olivares
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