Greenland’s geological past provides clues to current global warming

 (Image: Pixabay CC0)
(Image: Pixabay CC0)
Sediments taken from beneath an ancient ice core reveal that at least 20% of Greenland was green 416,000 years ago, corresponding to a recent past on the geological scale. The study, published in the journal Science, was carried out by an international team of scientists, including the Laboratoire de Glaciologie of the Université Libre de Bruxelles. It contributes to a better understanding of the impact of the melting of the Greenland ice sheet, and strengthens future projections of sea-level rise.

A new study published in the journal Science shows that at least 20% of Greenland was deglaciated in the recent geological past (around 416,000 years ago). The island’s perimeter was then covered by a mixed landscape of ice, tundra, trees and roamed by woolly mammoths.

The results of this recent study provide a better understanding of the stability of the Greenland ice sheet over the last two and a half million years, under climatic conditions not very different from today’s: moderate warming (with average global temperatures 1 to 1.5°C above pre-industrial values) for 30,000 years, from 420,000 to 390,000 years ago. These conditions led to the melting of at least 20% of the total volume of the Greenland ice sheet.

This ground-breaking research was carried out by an international group of scientists with complementary expertise (glaciologists, sedimentologists, geochronologists, geochemists). Jean-Louis Tison, researcher at the Laboratoire de glaciologie, Faculty of Science, Université libre de Bruxelles, was part of the frontline team that handled, described and carried out the first analyses of these exceptional sub-glacial archives.

"At that time, Greenland’s melting caused sea levels to rise by at least 1.5 meters, despite atmospheric carbon dioxide levels well below today’s (280 vs. 420 ppm)," explains study co-author Jean-Louis Tison, before continuing: "this tells us that the Greenland ice sheet is sensitive to human-induced climate change and will be vulnerable to rapid melting over the coming centuries. "

Knowing that Greenland has the potential to raise global sea levels by almost 7 meters, this data is crucial for refining numerical modelling of the ice caps, enabling us to anticipate their evolution in the near future. This is crucial to the reliability of future projections of sea level rise at the end of the century.­actus/rech­erche/le-p­asse-geolo­gique-du-g­roenland-n­ous-inform­e-sur-le-r­echauffeme­nt-climati­que-actuel