Greenland's glaciers are losing far more ice than previously thought

Recent research has revealed alarming new details about the state of Greenland’s glaciers. According to a study led by scientists at NASA’s Jet Propulsion Laboratory, the Greenland ice sheet has lost approximately 20 percent more ice than previously estimated. 

This discovery not only raises concerns about sea level rise but also poses potential challenges for ocean circulation patterns.

Glacier retreat 

The study, which spanned from 1985 to 2022, involved a comprehensive analysis of glacier retreat across the entire ice sheet. Utilizing nearly a quarter of a million pieces of satellite data, the researchers observed significant retreat in 179 out of 207 glaciers. 

Chad Greene, a glacier scientist at JPL and the study’s lead author, explained the process. “When the ice at the end of a glacier calves and retreats, it’s like pulling the plug out of the fjord, which lets ice drain into the ocean faster.”

Global sea level rise 

Previous research was primarily focused on direct contributions of the Greenland Ice Sheet to global sea level rise through ice flow and melting. 

The Intergovernmental Panel on Climate Change, citing the Ice sheet Mass Balance Inter-comparison Exercise (IMBIE), estimated a loss of 5,390 billion tons of ice from 1992 to 2020, contributing about 0.531 inches to global sea levels. 

Additional ice loss 

However, this did not account for the ice lost due to the retreat of terminal glaciers at the edges of Greenland. The new study fills this gap, revealing an additional loss of about 1,140 billion tons of ice – a staggering 21% more than the IMBIE assessment.

While this additional ice loss has not directly contributed to sea level rise due to its subsea level origin, it signifies a substantial influx of fresh water into the ocean. This influx could potentially disrupt the Atlantic Meridional Overturning Circulation, a critical component of the global oceanic “conveyor belt.” 

Such a disruption could have far-reaching impacts on global weather patterns and ecosystems, noted the researchers.

Critical new insights 

The study revealed that Greenland’s ice extent remained relatively stable from 1985 to 2000 but then experienced significant recession. 

The Zachariae Isstrom glacier lost the most ice, followed by Jakobshavn Isbrae and Humboldt Gletscher. Interestingly, only one glacier, Qajuuttap Sermia, showed any growth, but its gains were insufficient to offset the losses elsewhere.

A crucial finding of the study is the correlation between Greenland’s glaciers with large seasonal fluctuations in their ice fronts and the extent of overall retreat. This suggests that glaciers which are most sensitive to summer warming are likely to be the most affected by climate change in the future.

Study significance 

JPL cryosphere scientist Alex Gardner, a co-author of the paper, emphasized the significance of the study’s approach. By synthesizing big data, the study provided a systematic and comprehensive view of the ice sheet over time, as well as new insights into its behavior.

“Previously, we had bits and pieces – lots of local studies,” said Gardner. “But what this study offers is a systematic and comprehensive view that has led to some pretty significant insights that we didn’t have about the ice sheet before.”

The study is published in the journal Nature.

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