Past Greenland Ice Sheet Melting May Reveal Future Sea-Level Rise

Greenland is melting, so what does this mean for the future? In order to find out, a team of scientists looked to the past and quantified how the Greenland Ice Sheet reacted to a warm period that occurred 8,000 to 5,000 years ago.

Although rising global sea-levels will be an issue in the future, the researchers decided to focus on how fast the Greenland Ice Sheet reacted to past warming. For six summers, the scientists cored lakes in the ice free land surrounding the Greenland Ice Sheet. These lakes acted as valuable archives, storing glacial meltwater sediments in periods where the ice is advanced.

"It has been hard work getting all these lake cores home, but it has definitely been worth the effort," said Nicolaj Krog Larsen, one of the researchers, in a news release.

The size of the Greenland Ice Sheet has varied since the Ice Age ended about 11,500 years ago. Understanding its response to the warmest period, which is when temperatures were two to four degrees Celsius warmer than they are today, could help scientists learn what we could expect in the future.

In this case, the researchers found that the ice had its smallest extent during the warming period 8,000 to 5,000 years ago. The scientists then reviewed all available ice sheet models and chose the ones that best reproduced the reality of past warming.

The researchers found that during this period, the ice sheet was losing mass at a rate of 100 gigatons per year for several thousand years. This delivered the equivalent of 16 centimeters of global sea-level rise. In comparison, ice loss in the last 25 years has varied between 0 to 400 Gigaton per year, and it's expected that the Arctic will warm further and cause even more ice loss by the year 2100.

The findings reveal that we can expect rising sea-levels in the future. Because we now know how the Greenland Ice Sheet acted in the past, researchers can now estimate how quickly melting might occur in the future.

The findings are published in the journal Geology.

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