Scientists investigating how Antarctica’s ice sheet retreated in the distant past have turned to an innovative approach: studying the genes of cold-ocean octopuses.
new analysis Published in Thursday Science Magazine Researchers discovered that this geographically isolated population of eight-limbed marine creatures interbred freely about 125,000 years ago, when global temperatures were similar to today. This suggests that there were ice-free corridors.
The findings suggest that: west antarctic ice sheet (WAIS) is closer to collapse than previously thought, with long-term sea level rise expected to rise by 3.3 to 5 meters could occur, the authors said.
Lead author Sally Lau from Australia’s James Cook University told AFP that as an evolutionary biologist who studies marine invertebrates, “I understand DNA and biology and apply it as a proxy for past changes in Antarctica.” I’m doing it,” he said.
He said the Tarkett octopus made an ideal candidate for WAIS research. That’s because science has already figured out basic information about this octopus, such as the species’ 12-year lifespan and the fact that it appeared after about four years. A million years ago.
They are about 0.5 feet (15 centimeters) long without arms, weigh about 1.3 pounds (600 grams), and lay relatively few but large eggs on the ocean floor. This means that parents must go to great lengths to ensure their offspring hatch, a lifestyle that avoids long-distance travel.
Some modern habitats are also restricted by circulating ocean currents, or gyres.
By analyzing the genome-wide DNA sequences of 96 samples, commonly collected carelessly as fishery bycatch and then sitting in museum archives for 33 years, Lau and colleagues were able to connect Weddell, Amundsen, and Roth. discovered evidence of a trans-Antarctic sea route. Ocean.
The history of genetic admixture indicates that WAIS collapsed at two separate points in time. The first was the mid-Pliocene, 3 million to 3.5 million years ago, scientists were already sure, and the last was a warm period called the Last Interglacial. From 129,000 to 116,000 years ago.
“This was the last time the Earth was about 1.5 degrees warmer than pre-industrial levels,” Lau said. Human activity, mainly due to the burning of fossil fuels, has so far increased global temperatures by 1.2 degrees compared to the late 1700s.
“The turning point for the future collapse of WAIS is near.”
Before the new science paper was published, there were some studies suggesting that WAIS had collapsed at some point in its past, but relatively low-resolution genetic and geological data made it difficult to conclusively suggest that WAIS had collapsed at some point in its past. It was far from anything.
“This study provides empirical evidence that the WAIS collapsed when global average temperatures were similar to today, and suggests that a tipping point for future WAIS collapse is near.” are writing.
A sea level rise of 3.3 meters would dramatically change the world map as we know it, submerging low-lying coastal areas everywhere.
In an accompanying commentary, Andrea Dutton of the University of Wisconsin-Madison and Robert DeConte of the University of Massachusetts describe the new study as “pioneering” and raise interesting questions about whether ancient history will repeat itself. He added that he was throwing.
But they are wondering whether past ice sheet collapses were caused solely by rising temperatures or whether other variables, such as changes in ocean currents and the complex interactions between ice and the solid Earth, were also at play. He warned that important questions remain unanswered.
It’s also unclear whether sea levels will continue to rise over thousands of years, or whether they will rise more rapidly.
But such uncertainty is no excuse for government inaction. climate change “And this latest evidence from octopus DNA adds another card to an already unstable house in the sand,” the researchers wrote.
Recent news about Antarctic ice
The study comes about a month after scientists confirmed that: world’s largest iceberg On Friday, it was “on the move” after being trapped on the ocean floor for 37 years. Recent satellite images show an iceberg called . A23aAccording to the British Antarctic Survey, it has now passed the northern tip of the Antarctic Peninsula and is heading towards the Southern Ocean.
The results of the survey were announced earlier this month. dramatic video Footage taken by the ship’s crew also included drone footage of a pod of killer whales swimming alongside a huge iceberg.
The weight of the iceberg is Approximately 1 trillion tonsaccording to data from the European Space Agency (ESA).
The iceberg, which covers about 4,000 square kilometers (1,500 square miles), broke off from the Antarctic coastline in 1986 but later ran aground in the Weddell Sea, according to the BBC. report.
Meanwhile, in October, scientists revealed they had discovered a vast and hidden landscape of hills and valleys carved by ancient rivers. “Frozen in time” Under the ice of Antarctica for millions of years.
“This is an undiscovered landscape. No one has ever seen it before,” says Dr. the studyhe told AFP.
Jamieson said the land beneath the East Antarctic ice sheet is less well known than the surface of Mars.
The area spans 32,000 square kilometers (12,000 square miles) and was once home to trees, forests, and possibly animals.
But then ice appeared and “frozen over time,” Jamison said.
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