Thursday , June 24 2021

The ancient plants reveal Arctic summers that have not been hot for 115,000 years



Over the last decades, the glaciers and ice caps of Baffin Island in Arctic Canada have drastically retreated, revealing ancient landscapes that have probably been covered with ice for about 115,000 years.
Photograph: Gifford Miller, University of Colorado Boulder / INSTAAR

The newest sign of how excited the Arctic is: the moss, who has not seen the light of the day in at least 40,000 years, collapses from the ice caps on the Canadian island of Baffin, thanks to the ever sweeter summers. Based on this and other evidence, the research published in Nature Communications shows that the Canadian Arctic summer was not as hot in 115,000 years or more.

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

"This study shows that wow, we are exhibiting 120,000-year-old landscapes," said Simon Pendton, lead author of the University of Colorado's Arctic and Alpine Research Institute. "Our last century of warmth is probably greater than any century over the past 120,000 years."

Preserved ancient moss, collected from the field of the retreating ice cap on Baffin Island.
Photograph: Gifford Miller, University of Colorado Boulder / INSTAAR

To reach that conclusion, Pendleton and his colleagues relied on the ice of Bafin Island and the strange geographic features that allowed him to reveal his secrets. The island is home to deep fjords and tall fabrics, the last of which is covered with ice caps. Ice hats are huge pieces of ice, like glaciers, but there is one major difference. Where the glaciers flow and ground on the ground beneath them, the ice caps are static. This means that everything that is on the ground when they are formed is retained instead of being ground to dust.

For centuries the ice has occupied a plateau and walls on Bafin Island. In some summers it would melt, but in general the low temperatures and the snow kept things in balance. Now, climate change has disturbed this equilibrium, causing the Arctic to warm up twice as fast as the rest of the world. This has led to more summer melt, which reveals moss and mist in the periphery of ice 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 on the wild side, some mosses were returned back to the labs and returned as an arctic zombie).

But here is something: 40,000 years are near the end of history that you can explore from radiocarbon dating. It also happens to hit the middle of the ice age. This made Pendleton and his colleagues look for other records, including nearby ice measurements from Greenland. By cross-referencing the plants, they show that the area has been covered with ice for much longer than 40,000 years, and that the summer of our new climate is probably softer than anything in about 115,000-120,000 years.

As the ice caps go further, they can expose even more ancient landscapes. By refining their measurements, scientists can then predict how the Arctic will look, as climate change continues to change it. Pendleton said even without radiocarbon dating, it is clear how quickly Baffin Island moves into a new state. Every year, changes become more visible with the naked eye.

"To see it and walk on the ice cap and find out that we are in a time setting out landscapes that have not seen sunlight for 120,000 years, it has a profound effect," he said.


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