A team of researchers studied fossils of southern elephant seal (Mirounga leonina) along the coast of Victoria Land, in the Ross Empire, a huge region of Antarctica. The analysis revealed that animals of this species lived there when the region was much warmer, during the middle Holocene period, which began about 11,600 years ago and extends to the present.
At the time, a reduced amount of ice covered the Ross Sea, the scientists report in an article published Feb. 7 in the journal Quaternary Science Reviews.
Scientists led by Brenda Hall, a professor at the College of Earth and Climate Sciences at the University of Maine, USA, collected the mummified remains and skeleton of an elephant seal, as well as its melted skin buried under rocks and snow.
The group recovered 305 samples, which were dated and radiocarbon tested to ensure they were free of ancient DNA. The results showed that the animals not only occupied the Ross Sea, but also existed on the coast of Victoria Land from about 7,000 to 5,000 years ago.
Today the coastal region is virtually free of elephant seals and even penguins in many places due to the permanent sea ice shelves frozen on its shores. Elephant seals are now found mostly on islands north of the Ross Sea.
Previous research from the University of Maine found the remains of these mammals on beaches, indicating that the species thrived in the area in the warm Holocene periods. The new study shows that the animals occupied such beaches in a warm period before extensive sea ice pushed them away from the current coast.
“Today, southern elephant seals tend to hunt in areas warmer than the Ross Sea,” Hull says in a statement. “We were able to use the presence of their withered skin and hair, as well as some bones and mummies dried by the polar winds, to show that elephant seals made the Ross Sea their home.”
According to the professor, ancient heat in the sea may have prompted the retreat of the West Antarctic ice sheet over the past 8,000 years. “Future warming may continue to push back the ice. However, ocean temperature may not be the whole story,” warns the expert.
Scientists think more research is needed, but they have found some elephant seals from a much earlier period, before the last ice age. This suggests that warm water may have been present during ice sheet build-up in the Ross Sea.
If the presence of warm ocean temperatures is confirmed immediately before and possibly even during the formation of the last glacial extreme site, this indicates that factors other than lower ocean temperatures, such as lower sea levels, could be critical in causing an ice sheet to advance on Ross Empire. .
Studying the response of ice sheets to past warming is essential to understanding how they are responding to the current climate crisis. “Under future global warming, warm ground ocean water and thus melt is likely to increase around Antarctica due to southward movement of westerly winds and increased meltwater production or strong east polar winds,” the researchers say in the article.
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