The South Pole, the most isolated part of the planet, is also one of the fastest heating, scientists said Monday, with the increase in surface air temperature since the 1990s at a rate three times faster. than the world average.
While the warming could be the result only of natural climate change, the researchers said, the effects of human-caused warming are likely contributing to it.
The pole, home to a United States research base in the high, icy void of inland Antarctica, has heated to about 0.6 degrees Celsius, or 1.1 degrees Fahrenheit, per decade in the past 30 years, researchers reported in a Article published in Nature Climate change. The global average during that time was approximately 0.2 degrees Celsius per decade.
Although parts of coastal Antarctica are losing ice, which contributes to rising sea levels, the pole is not in danger of melting, as the average temperature throughout the year is still minus -50 degrees Celsius. But the finding shows that no place is unaffected by change on a warming planet.
Analyzing meteorological data and using climate models, the researchers discovered that the increase in temperatures is the result of changes in atmospheric circulation that originate thousands of kilometers away in the western tropical Pacific Ocean.
“The South Pole is heating up at an incredible rate, and is primarily driven by the tropics,” said Kyle R. Clem, postdoctoral researcher at Victoria University of Wellington in New Zealand and lead author of the study.
While it is highly likely that climate change resulting from emissions of carbon dioxide and other greenhouse gases has played a role, the analysis showed that natural climate variability could explain all of the extreme change in temperature, effectively masking any contributions. caused by man.
“The interior of Antarctica may be one of the few remaining places on Earth where the anthropogenic signal cannot be easily detected due to such extreme variability,” said Dr. Clem.
“But it is very, very unlikely that you will get such a strong warming trend without increasing greenhouse gases,” he added.
Post temperature records have been kept since 1957, when American first base was completed there. For decades, average temperatures were constant or decreased. The strong westerly winds surrounding the continent served as a barrier, preventing warmer air from entering the interior.
But that changed near the end of the 20th century, Dr. Clem said, when sea surface temperatures in the western tropical Pacific began to rise, part of a natural oscillation that occurs on a decades-long time scale.
Ocean warming warmed the air, causing high and low pressure waves in the atmosphere that reached the Antarctic Peninsula, more than 5,000 miles away. Scientists call these types of long-distance links teleconnections.
Along with strong westerly winds, which are part of another long-term pattern, the waves caused stronger storms in the Weddell Sea, east of the peninsula. These spinning, or cyclonic, storms carried warmer air from the South Atlantic Ocean into the interior of the continent.
The strongest storms in the Weddell Sea have also led to a recent decline in sea ice in the region.
Dr. Clem said warming was not uniform across the Antarctic plateau, the vast expanse that covers most of the interior, including the pole, with an average elevation of nearly two miles. But the only other permanent base on the plateau, Russia’s Vostok station about 800 miles from the pole, has also seen a rapid rise in temperatures, he said.
Waves of the tropical Pacific also had an effect on the Antarctic Peninsula, which for most of the late 20th century had been one of the world’s fastest warming zones. But in recent decades, the rate of warming has decreased significantly.
In an email message, two researchers from the University of Colorado, Sharon E. Stammerjohn and Ted A. Scambos, said that while the rest of the world has been steadily warming for the past five decades, Antarctica has undergone major changes. , and probably always has. None of the scientists participated in the research, but they wrote a comment on the study published in the same issue of the journal.
As ocean temperatures in the tropical Pacific shift toward cooling, they said, the warming rate at the South Pole will likely decrease as well, but not as much as it would have without man-made climate change.
In an interview, Dr. Stammerjohn said that “the warming at the South Pole is significant because it is the most remote place on the planet.”
“But it’s still never going to get over the freeze,” he said. “We still don’t have to worry too much about losing ice on the post. But the coasts are definitely another matter ”.
Especially along the coast of West Antarctica, warm water rising from the depth by the action of the wind is melting the ice shelves from below, ultimately leading to sea level rise.
Dr. Stammerjohn said there was increasing evidence that the way the planet is responding to warming was changing the atmosphere and ocean circulation on a large scale.
“And that is what contributes to the warmer waters at depth,” he said. “There will be a lot of variability superimposed on that, but the direction and projection would be towards more and more warm water and more loss of the ice sheet.”
“It is so easy to think that Antarctica is isolated and remote and that it will not respond to climate change,” said Dr. Stammerjohn. While the impact at the South Pole may not be as significant, the loss of ice along the coast has huge implications.
“It is the one that is going to change our sea level dramatically,” he said.
The warming at the South Pole, he said, is “the ultimate canary in the coal mine, one that we can no longer ignore.”
