Mathieu Morlighem: 'Many glaciers have been accelerating and thinning near the margin in recent decades'

A 2022 study led by Dartmouth professor Mathieu Morlighem, reveals that the Northeast Greenland Ice Stream (NEGIS) is losing ice at an alarming rate, which could lead to up to six times more sea-level rise by 2100 than previously projected. The data collected from Greenland's harsh interior suggests that other glaciers on the island might be facing a similar fate, indicating a potential profound change in global sea levels.

Morlighem, working with researchers from the Technical University of Denmark (DTU) and the University of California, Irvine have unveiled alarming findings about the NEGIS. According to an article about the study from Dartmouth, the loss of ice from Greenland's largest basin is occurring much faster than previously thought and could significantly accelerate global sea-level rise by the end of this century. The research highlights that the NEGIS could add a staggering half-inch or more of water to sea levels by 2100, a contribution equivalent to the entirety of Greenland ice sheet's impact during the past 50 years. The results indicate a potential six-fold increase in sea-level rise compared to current climate models, painting a far more dire scenario for the future.

Using a combination of satellite data, numerical modeling and GPS data collected over the past decade from Greenland's unforgiving interior, the study provides crucial insights into the ongoing ice loss in the region. The intrusion of warm ocean currents in 2012 led to the collapse of the floating extension of the NEGIS, intensifying ice flow and triggering rapid ice thinning that has extended nearly 200 miles inland from the Greenland coast.

"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," explained Morlighem, the Evans Family Distinguished Professor of Earth Sciences at Dartmouth and lead author of the study.

The research team's analysis revealed that the Greenland ice sheet might not be inherently more unstable than previously thought, but it appears to be more sensitive to environmental changes around the coast.

Professor Morlighem noted, "If this is correct, the contribution of ice dynamics to overall mass loss on Greenland will be larger than what current models suggest."

A key player in the study, Professor Shfaqat Abbas Khan from DTU Space, led a team that collected critical GPS data stretching inland on the NEGIS, behind the Nioghalvfjerdsfjord Gletscher and Zachariae Isstrøm glaciers. The GPS data was then compared to numerical models developed by co-author Youngmin Choi, a former graduate student in Morlighem's research group at UC Irvine who is now at NASA's Jet Propulsion Laboratory. Based on their findings, Morlighem and Choi projected the future dynamics of the NEGIS, leading to the alarming conclusion that the ice stream could lose six times more ice than previously estimated by existing climate models.

"We can see that the entire basin is thinning and the surface speed is accelerating. Every year, the glaciers we've studied have retreated farther inland, and we predict that this will continue over the coming decades and centuries," warned Khan. He added that even though winter 2021 and summer 2022 experienced particularly cold temperatures, the NEGIS glaciers have continued to retreat, and the region's limited precipitation prevents sufficient regeneration of the ice sheet to offset the ongoing melt.

The study's co-author, Professor Eric Rignot, emphasized that as these more precise observations of ice velocity changes are integrated into models, estimates of global sea-level rise, like the 8-to-38 inches projected by the UN Intergovernmental Panel on Climate Change by 2100, will likely need to be corrected upwards.

"We foresee profound changes in global sea levels, more than currently projected by existing models," said Rignot.

The research serves as a wake-up call for the scientific community and policymakers, highlighting the urgency of addressing climate change and its devastating impact on ice loss and sea-level rise. With the Greenland ice sheet contributing significantly more to rising sea levels than previously thought, immediate action and global cooperation are vital to mitigate the impending environmental crisis. As scientists continue to uncover critical insights into the dynamics of ice loss and its implications for our planet's future, the need for decisive action becomes clearer than ever before. The fate of the NEGIS and Greenland's ice sheet lies in the hands of humanity, and the time to act is now.