New research has found that Greenland may have been green and ice-free as recently as 416,000 years ago.
The study, published in the journal Science, raises concerns that Greenland’s ice sheets may not be as stable as previously thought and provides information on how the region’s landscape may react to climate change.
The researchers analyzed sediments extracted from ice cores collected in the region, which found evidence of leaves and mosses from the period.
This indicates that a large portion of the Greenland ice sheet melted when the Earth warmed moderately between 424,000 and 374,000 years ago, causing global sea levels to rise by five to 20 feet.
The research contradicts the widely held view that most of Greenland’s ice sheet has existed for at least a million years, if not longer.
Paul Bierman, a geologist and professor at the University of Vermont in the US, said: “This is really the first bullet-proof evidence that most of the Greenland ice sheet disappeared when it warmed.”
Ice cores are cylinders of ice drilled from glaciers and ice sheets that are essentially frozen time capsules, allowing scientists to reconstruct Earth’s climate from millions of years ago.
The ice core analyzed in the new study is 12 feet long and was drilled at Camp Century in northwest Greenland, which served as a secret US military base during the Cold War.
The ice sample was forgotten in a freezer for decades and was accidentally rediscovered in 2017.
The researchers also found that sediments in the ice core were deposited by flowing water during a warming period called marine isotope stage 11.
Along with being ice-free, Greenland may have changed to a tundra with tree-covered woolly mammoths or even a boreal forest.
The study’s authors said the study is important for understanding how the Greenland ice sheet will respond to future climate warming.
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The region’s ice sheets hold enough water to raise sea levels by up to 23 feet, putting every coastal city in the world at risk, scientists said.
Professor Bierman said: “Greenland’s past, preserved in 12 feet of frozen soil, suggests a warmer, wetter and largely ice-free future for planet Earth unless we can dramatically reduce atmospheric carbon dioxide concentrations.
“Four hundred thousand years ago there were no cities on the coast and now there are cities on the coast,” he added.
Professor Tammy Ritenour of Utah State University’s Department of Geosciences said: “If we melt just parts of the Greenland ice sheet, sea levels will rise dramatically.
“Driven by melting rates and high carbon dioxide responses, we’re looking at meters, maybe tens of meters, of sea level rise.”
Source by [Sky News]
