Greenland ice sheet far more sensitive to climate change than predicted, study finds

A new international study involving the University of Oulu reveals that the Greenland ice sheet responds far more dramatically to climate warming than previously estimated, potentially accelerating methane emissions and sea-level rise.

The research, published in Nature Geoscience, analysed meltwater samples collected along a 2,000-kilometre stretch of the ice sheet’s western edge. Using isotope analysis and radiocarbon dating, scientists traced methane released from beneath the ice to microbial activity in oxygen-free conditions, where microbes feed on decaying organic matter in subglacial sediments.

The methane was found to be between 1,500 and 4,500 years old, suggesting a large-scale release occurred during a warming period roughly 4,000 years ago. The findings indicate the ice sheet had retreated significantly beyond its current boundaries after the last ice age, exposing areas where boreal and tundra vegetation grew before the ice expanded again during a later cold period.

Professor Alun Hubbard of the University of Oulu warned that the study underscores the ice sheet’s vulnerability. “This is a stark reminder of the inevitable impact on sea-level rise and coastal flooding if greenhouse gas emissions aren’t curbed,” he said in a university statement. Hubbard noted the irony that retreating glaciers may themselves amplify methane emissions, further accelerating warming.

Researchers cautioned that subglacial methane reserves could be released as ice sheets melt and shrink, creating a feedback loop that intensifies climate change.