By combining paleoclimate data from the past 2,000 years with powerful computer modeling and field studies of lake sediments and tree rings, a team of scientists led by François Lapointe, a research assistant at the University of Massachusetts Amherst, has demonstrated the emergence of a poorly understood phenomenon known as atmospheric pressure. The lockdown has long affected temperature fluctuations in the Arctic.

As temperatures rise due to climate change, atmospheric obstructions will encourage increasingly severe weather events. The study focused on the Norwegian Arctic archipelago of Svalbard at the edge of the Arctic Ocean and Nature Communication.

It is well known that the Arctic is warming faster than the global average; this is a phenomenon known as Arctic amplification. But since 1991, Svalbard has seen a warming trend that is twice as large as the temperature increase in the Arctic. As a result, the archipelago is experiencing massive ice loss, heavy rainfall and landslides.

“We wanted to know why Svalbard was warming so much faster than the rest of the Arctic,” says Raymond Bradley, a distinguished professor at the University of Massachusetts Amherst and co-author of the study, and we wanted to see whether these trends would continue. “

To do this, they turned to lake sediments from Lake Linne on the west coast of Svalbard, which helped them reconstruct the warm and wet conditions of the last 2,000 years. What makes this lake unique is the presence of instrumentation that has been used since 2012 by UMass Amherst alumnus and co-author Michael Rethell, now a professor of earth and climate sciences at Bates College.

These devices track exactly when sediment enters the lake each year. During increasingly frequent downpours, sediment flows into the lake.

Lapointe and his team examined calcium levels in the sediments of Lake Linnaeus. Because much of the eastern land surrounding the lake consists of carbonate-rich soil, heavy rains mean that carbonate is washed into the lake, deposited in sediments on the lake bottom, and can be measured in sediment cores as a record of rainfall prolongation. about 2000 years ago.

When Lapointe and his colleagues compared all these historical and modern observations with meteorological records, they found a surprising correlation.

“The greatest rainfalls and warming in the past are associated with atmospheric blocking over Scandinavia and the Ural Mountains. Atmospheric blocking is when a high-pressure system around which air rotates clockwise stalls in a particular region (in this case in the north) of Scandinavia. With this high-pressure system, rains in Svalbard are often It is also associated with a low pressure system that settled over Greenland and rotated counterclockwise,” says Lapointe.

The two systems spin like a pair of interlocking gears, pulling warmer, wetter air from the mid-Atlantic into the Arctic and causing torrential rains on Svalbard. Since observational measurements began, Arctic blocking has increased, as has Arctic warming.

“It will be very interesting to see how atmospheric blocking will behave with further warming,” Lapointe adds. “Further increases are likely to worsen the effects of flooding and natural disasters on Svalbard.”

Such predictions about the future of Svalbard cause concern. Although the archipelago has a year-round population of only 2,650, the islands’ breathtaking scenery and unique wildlife attract more than 130,000 visitors annually.