قالب وردپرس درنا توس
Home / Science / The retreat of the ice left the Arctic landscape untouched for 120,000 years

The retreat of the ice left the Arctic landscape untouched for 120,000 years



The retreat of the Arctic glaciers shows landscapes that have not seen the sun for nearly 1

20,000 years.

These rocky outlooks have probably been covered with ice since the Eemian, a period in which average temperatures were up to 3.6 degrees Fahrenheit (2 degrees Celsius) warmer than today and sea levels up to 9 meters (9 feet) higher.

"The last century of heat is likely to be greater than every century before this 120,000-year-old history," said study leader Simon Pendleton, a graduate student at the University of Colorado at the Boulder Institute of Arctic and Alpine Research. [See Stunning Photos of Baffin Island Glaciers]

19659007] More from LiveScience

Pendleton and his colleagues strolled through these ancient landscapes while sampling on Baffin Island, Canada, surrounded by dramatic fjords, but the interior of the island is characterized by relatively shallow tundra levels. 19659005] These tundra plains are covered with thin ice caps, and because the landscape is so shallow, the ice caps do not flow like typical glaciers, Pendleton told Live Science, instead they simply sit on the underlying rock and ground and keep everything under them like the glass

What remains are tiny arctic plants and moss e, who last lived when the ice covered the land. When the ice melts, says Pendleton, it releases this ancient, delicate vegetation. Wind and water destroy the long-lost plants within a few months, but if researchers can reach them first, they can determine the age of vegetation by using carbon dating to decay the isotope of carbon, carbon-14. (Carbon-14 has eight neutrons in the nucleus and not six like ordinary carbon.) Because scientists know how fast carbon-14 decays – and plants absorb carbon-14 through photosynthesis – they can use the amount of isotope in an organic sample To determine his age.

Pendleton and his colleagues took 124 samples from 30 locations around eastern Baffin Island, all within about 1 m (3 feet) of the edge of the modern ice cap – the area that was last exposed by melt and where remnants were from ancient ones Plants had not been removed yet.

They found that all their samples were at least as old as the oldest age that can detect radiocarbon dating: 40,000 years. This is a direct indication that the plants were under ice for at least as long, the researchers reported on January 25 in the journal Nature Communications.

Visible change

The vegetation measurements could be confirmed by the researchers by measurements minerals in the nearby rock, which also suggest a continuous ice cover of at least 40,000 years. It is almost certain that Baffin Island will be buried in the ice for much longer, Pendleton said. Forty thousand years ago, the world was in the middle of the last ice age. If it is as hot as today to melt ice that lasts so long, the last period found in the Arctic is nearly 120,000 years ago, Pendleton said. The chances are great that some of the landscapes uncovered today have been buried since this warm interglacial period. [ On Ice: Stunning Images of Canadian Arctic ]

" We know that dramatic changes will occur and continue to take place, but I do not know that we found evidence that we now see landscapes and temperatures similar to those of the last interglacial period "said Pendleton.

The changes on Baffin Island are undeniable even to the naked eye, Pendleton said. The research team sampled the island in 2005, 2013, 2014 and 2015. Year after year, Pendleton says, the retreat of the ice was evident. The researchers would use GPS to determine their earlier sampling point, which had once been at the edge of the ice. In some places, Pendleton said, they would find the length of a football field from the new edge of the ice.

"To stand there and see that change is, I do not have a good word for it," said Pendleton. "It's kind of breathtaking."

Originally published on Live Science .


Source link