New research gives more damning assessment of the rising sea levels

Global warming, climate change, Greenland and Antarctica are among the key words whenever pressing environmental concerns are discussed. A new study that reveals Greenland’s largest ice sheet is thawing at a much higher rate than expected is yet another warning sign. Published in the journal Nature on November 9, the research has suggested that the accelerated thawing will add six times more water to the rising sea levels than previously thought. And the trend may not be limited to Greenland, scientists worry.

It is pertinent that the study has been released while countries are negotiating at the 27th Conference of Parties to the United Nations Framework Convention on Climate Change (COP27) in the Egyptian coastal city of Sharm El-Sheikh. The summit, building on the outcomes of last year’s COP26 climate change gathering in Glasgow, Scotland, seeks to identify solutions for a vast range of climate-related emergencies, including the energy crisis and the increasing severity of extreme weather events.

The study used GPS measurements and computer modelling to estimate how much ice is being lost due to climate change from the Northeast Greenland Ice Stream (NEGIS), a prominent ice flow that drains ice and meltwater from Greenland’s inland ice-covered basin. NEGIS, a titanic conveyor belt of solid ice that crawls about 600km out of the landmass’s hinterland and into the sea, drains about 12% of the country’s entire ice sheet and contains enough water to raise global sea level more than a meter. Near the coast, NEGIS splits into two glaciers, Nioghalvfjerdsfjord and Zachariae Isstrøm. The calculations revealed that, since 2012, NEGIS melting has been speeding up so much that by the end of this century, it will add more than 1.3cm of water to the global ocean level. That’s equivalent to the past 50 years’ worth of Greenland’s entire contribution to sea level rise.

“It’s not something that we expected,” says Shfaqat Abbas Khan, a glaciologist at the Technical University of Denmark in Kongens Lyngby. “Greenland and Antarctica’s contributions to sea level rise in the next 80 years will be significantly larger than we have predicted until now.” While frozen, these glaciers keep the ice behind them from rushing into the sea, much like dams hold back water in a river. When the ice shelf of Zachariae Isstrøm collapsed about a decade ago, scientists found that the flow of ice behind the glacier started accelerating. Scientists were able to measure the thinning as far as 300km from Greenland’s northeastern coast where NEGIS meets the ocean.

“Many glaciers have been accelerating and thinning near the margin in recent decades — GPS data helped us detect how far inland these changes happening near the coast propagate,” study co-author Mathieu Morlighem, a professor of Earth Sciences at Dartmouth College in New Hampshire, said in a statement (opens in new tab). “If this is correct, the contribution of ice dynamics to overall mass loss on Greenland will be larger than what current models suggest.” Similar trends might be underway in other parts of the Greenland ice sheet as the whole system might be much more sensitive to changes happening in coastal areas than previously thought.

The study found that the accelerating melting continued even throughout the winter of 2021 and the summer of 2022, which were unusually cold in Greenland, suggesting the process will be quite difficult to stop. Khan and his colleagues plan to investigate inland sections of other large ice flows in Greenland and Antarctica, with the hopes of improving forecasts of sea level rise.

The calculations revealed that by the end of this century, more than 1.3cm of water will be added to the global ocean level