Greenland, Climate | Greenland has been ice-free before – that it could happen again, researchers worry

Once upon a time, Greenland was actually green, according to researchers, who believe the island was ice-free about 400,000 years ago. The finding may change our view of climate change.

Greenland is the world’s largest island, and is almost completely covered with a layer of ice that is around three kilometers at its thickest. If all the ice were to melt today, the sea level would rise by about seven meters.

But relatively recently, in a scientific time perspective, the island was free of ice and covered by lush nature.

Read also: Study: The Greenland ice is melting seven times faster than before

Tests of soil samples from the secret American Greenland base Camp Century show that this was the case around 400,000 years ago. The samples were taken from the US military, which in the 60s drilled down through a 1,400 meter thick layer of ice.

Lying on ice

For unknown reasons, the soil samples were frozen and stored in Denmark. Only in 2017 were they finally analyzed by a team from the University of Vermont.

Geologist Paul Bierman says he found something in the ground he could not identify, and he asked colleague Andrew Christ to take a look.

– He looked down into the microscope and made an exclamation. It was a branch piece, which had been under a kilometer-thick layer of ice. Incredible! says Bierman to the news agency AFP.

Read also: Climate goals seem to be missing in Oslo

Bierman and colleagues now present the findings from the study in the renowned research journal PNAS. They conclude that the soil samples date from a time when Greenland was covered with moss, lichen and perhaps even trees.

Fragile than expected

The finding gives cause for concern among researchers. Until now, it has been thought that there will be much more CO2 in the atmosphere before the Greenland ice sheet collapses than the current 415 parts per million.

But 415 parts per million is historically high, and a very rapid increase from 285 parts per million when fossil fuels began in the mid-19th century.

– The natural variations over a million years are between 180 and 290 parts per million, Bierman says.

The final conclusion is that the ice cover is even more fragile than previously thought. This means that if humans continue to burn fossil fuels, they can reach the threshold much faster where they experience extensive ice melting.

Consequences for coastal areas

The forecast from the United Nations’ Intergovernmental Panel on Climate Change (IPCC) used today estimates that sea levels will rise by around one meter until the turn of the century, ie when today’s children are old.

Hundreds of millions of people will be affected in low-lying areas worldwide, including coastal areas in Scandinavia. In Norway, sea level rise is expected to have the greatest consequences in Sørlandet, Vestlandet, Lofoten and Finnmark, according to the Norwegian Environment Agency’s 2015 report «Future sea level and storm surge in Norwegian coastal municipalities».

But this is a very limited estimate of the seven meters you will see if the ice in Greenland melts and Greenland turns green again.

(© NTB)


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