The clue is in the study title: The importance of Canadian Arctic Archipelago gateways for glacial expansion in Scandinavia.
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A new study led by University of Arizona researchers may have solved two mysteries that have long puzzled paleo-climate experts (says Phys.org): Where did the ice sheets that rang in the last ice age more than 100,000 years ago come from, and how could they grow so quickly?
Understanding what drives Earth’s glacial–interglacial cycles—the periodic advance and retreat of ice sheets in the Northern Hemisphere—is no easy feat, and researchers have devoted substantial effort to explaining the expansion and shrinking of large ice masses over thousands of years.
The new study, published in the journal Nature Geoscience, proposes an explanation for the rapid expansion of the ice sheets that covered much of the Northern Hemisphere during the most recent ice age, and the findings could also apply to other glacial periods throughout Earth’s history.
About 100,000 years ago, when mammoths roamed the Earth, the Northern Hemisphere climate plummeted into a deep freeze that allowed massive ice sheets to form. Over a period of about 10,000 years, local mountain glaciers grew and formed large ice sheets covering much of today’s Canada, Siberia and northern Europe.
While it has been widely accepted that periodic “wobbling” in the Earth’s orbit around the sun triggered cooling in the Northern Hemisphere summer that caused the onset of widespread glaciation, scientists have struggled to explain the extensive ice sheets covering much of Scandinavia and northern Europe, where temperatures are much more mild.
Unlike the cold Canadian Arctic Archipelago where ice readily forms, Scandinavia should have remained largely ice-free due to the North Atlantic Current, which brings warm water to the coasts of northwestern Europe.
Although the two regions are located along similar latitudes, the Scandinavian summer temperatures are well above freezing, while the temperatures in large parts of the Canadian Arctic remain below freezing through the summer, according to the researchers.
Because of this discrepancy, climate models have struggled to account for the extensive glaciers that advanced in northern Europe and marked the beginning of the last ice age, said the study’s lead author, Marcus Lofverstrom.
“The problem is we don’t know where those ice sheets (in Scandinavia) came from and what caused them to expand in such a short amount of time,” said Lofverstrom, an assistant professor of geosciences and head of the UArizona Earth System Dynamics Lab.
Continued here.
via Tallbloke’s Talkshop
June 25, 2022, by oldbrew
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