Greenland Was Nearly Ice-Free For 280000 Years

Posted: Dec 8 2016, 4:21am CST | by , in News | Latest Science News

 

Greenland Was Nearly Ice-Free for 280000 Years
Scientists drilled nearly two miles down through the summit of the Greenland ice sheet (white dot, left), to reach bedrock. Isotopes found in the rock indicate that this site and most of Greenland were nearly ice free (right) during the recent geologic past. Credit: Getty Images
  • Greenland used to be Free of Ice Once Upon a Time
 

Greenland used to be free of any ice once upon a time. In fact, for approximately 280,000 years, it had its bedrock exposed.

A million years ago, Greenland was not the huge icy island it happens to be today. It was ice-free and its land was exposed for a period amounting to 280,000 years which is a lot of time.

Throughout the duration of this exposure to the elements, over 90% of the ice cover could have been laid bare. While there have been reports of Greenland being without ice in the past, this is the first time that this lengthy period of time has been mentioned with such accuracy.  

The finding exposes how Greenland’s ice was once not there and so it is a lesson to us modernists that even now, the ice could melt leaving Greenland free of any of the ice sheets.

The future stability of Greenland in times of global warming is in doubt. The scientists had gathered their information from isotopes.

These consisted of atoms of the same elements but with a different number of neutrons. They were unearthed from bedrock supplies. These included beryllium 10 and aluminum 26. 

They happen to be brought into existence due to the influence of cosmic rays. These isotopes thus only occur when the rocks which hold them are exposed to view.

They can lend us valuable clues about when and for how long Greenland was free of ice. The isotopes actually were retrieved from the land during the Greenland Ice Sheet (GIS) Summit in 1993.

The minerals obtained this way are no less precious than moon rocks. When this core was probed several years ago, the investigators noticed the presence of the aforementioned isotopes. The minerals were mixed with acid all the better to observe the atoms underneath.   

It was the isotope beryllium 10 that lent the scientists a clue or two regarding the ice free state. To gauge how long such an ice free state had remained extant, this isotope was compared to aluminum 26.

The ratio of the two was 7:1. Yet beryllium 10 decays very fast. Until 1.1 million years ago, most of Greenland had been exposed to sunlight. There had been no ice sheets.

The ice had shown patterns of build-up and degradation over time. The prehistory of Greenland is quite different from the conditions that prevail in it today.

The findings appear this week in the leading journal Nature.

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<a href="/latest_stories/all/all/20" rel="author">Sumayah Aamir</a>
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