Ancient plants reveal that Arctic summers are not as hot in 115,000 years


The last sign of how the Arctic is fucked: Moss that have not seen the light of day for at least 40,000 years are falling from the ice caps on Baffin Island, Canada, thanks to increasingly mild summers. Based on this and other lines of evidence, the published research Communications of nature on Friday suggests that the summers of the Canadian Arctic were not as hot in 115,000 years or so.

Even in the wild world of statistics on how climate change is transforming the Arctic, it stands out.

"This study indicates that we are exposing landscapes with 120,000 years," said lead author Simon Pendleton of the Institute of Arctic and Alpine Research at the University of Colorado. Gizmodo. "Our last century of heat is likely to be greater than any other century in the last 120,000 years."

To reach this conclusion, Pendleton and his colleagues relied on the ice of Baffin Island and the bizarre peculiarities of geography that allowed him to reveal his secrets. The island is home to deep fjords and high plateaus, the last of which are covered with polar caps. Ice caps are huge chunks of ice, like glaciers, but there is a fundamental difference. Where the glaciers run and crumble the earth beneath them, the polar ice caps are static. This means that whatever is on the ground when it is formed is preserved instead of being powdered.

For centuries, ice had occupied the plateaus and walls of Baffin Island. In some summers it would melt, but in general the low temperatures and the snow kept things practically in balance. Now, climate change has disrupted that balance, causing the Arctic to warm up at twice the rate of the rest of the world. This led to more summer melting, which exposed moss and lichen on the banks of the polar caps.

Pendleton and others collected samples of about 30 ice caps and conducted radiocarbon dating to determine their age. The findings show that mosses are at least 40,000 years old (and, in a note on the wild side, some of the mosses were brought back to the labs and brought back to life as Arctic zombie plants).

But here's the thing: 40,000 years are close to history that you can test with radiocarbon dating. It also happens to be in the middle of a glacial period. This led Pendleton and his colleagues to scour other records, including measurements of ice near Greenland. By making cross-references to the plants, they show that the area has been covered by ice much more than 40,000 years and that the summers of our new climate are probably more devastating than anything in about 115,000 to 120,000 years.

As the ice caps recede further, they could expose even older landscapes. By refining their measurements, scientists can predict how the Arctic will look, as climate change continues to reshape it. Pendleton said that even without radiocarbon dating, it is clear how quickly Baffin Island is shifting to a new state. Each year, the changes become more visible to the naked eye.

"To be able to see it and walk on the ice cap and understand that we are at a time that is exposing landscapes that have not seen sunlight in possibly 120,000 years, this has a profound effect," he said.


Source link