Wednesday, 28 March 2018

ANTARCTIC ICE SHEET MAY HAVE COLLAPSED 120,000 YEARS AGO SAYS NEW STUDY

This article explains the details. Below is an exerpt.

"The new project could also cast light on some lingering suspicions—that even though the Ross Ice Shelf seems stable today, it has actually undergone some dramatic collapses in the recent past. (Learn about the Maine-size hole in Antarctica.)

Reed Scherer made this discovery back in 1998 while studying mud that had been plucked from beneath the West Antarctic Ice Sheet, through another borehole, 100 miles inland from the back edge of the ice shelf.

Scherer, a micro-paleontologist now at Northern Illinois University in DeKalb, found this subglacial mud chockablock full of microscopic diatom shells—beautiful glassy objects, reminiscent of fine vases. They were the ancient remains of photosynthetic organisms that had once lived in the sea before dying and settling to the bottom.

Some of those dead diatoms were only a few hundred thousand years old, leading Scherer to an astounding conclusion: this area, now covered by 3,000 feet of ice, had recently been open sea, bathed in life-sustaining sunlight that could support the diatoms’ growth. This suggested that the entire Ross Ice Shelf, and much of the ice behind it, had collapsed.

The Ross Ice Shelf “has come and gone probably many times in the last million years,” says Scherer. It likely collapsed during a warm period 400,000 years ago. But he believes it could also have collapsed as recently as 120,000 years ago, the last time that temperatures were about as warm as they are today."

It is interesting to read that they accept that temperatures were as warm as today only 120,000 years ago, though this means they deny the medieval warm period existed only a thousand years ago.

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