Methane released from beneath the Greenland Ice Sheet has been linked to a warmer period thousands of years ago, raising concerns about future climate feedbacks, according to a study published in Nature Geoscience.
In a new paper, an international team lead by scientists from Charles University, Czechia, has brought evidence linking widespread release of methane (CH4) – a strong greenhouse gas – from the Greenland Ice Sheet (GrIS) to a warmer period 9-4 thousand years ago. CH4 has been detected at retreating glacier margins worldwide, raising concerns about potential climate feedbacks associated with their widespread retreat, but this is the first time that a study has systematically investigated the whole margin of an entire ice sheet.
The scientists collected samples of glacial meltwater across a transect spanning the entire 2000 km-long western margin of the GrIS and used stable isotope analysis and radiocarbon dating to constrain the origin and age of dissolved CH4 exported by the meltwater.
The CH4 was found to be between 1500-4500 years old and produced biologically by microbes called methanogenic archaea as an end product of organic matter degradation under anoxic conditions. This suggests the ice sheet retreated significantly inside its present margins during the Holocene. Tundra vegetation could grow and accumulate organic matter in the newly exposed areas, which was subsequently overridden by the readvancing ice in the following colder period. The retreat also suggests a highly dynamic ice sheet, one that is more sensitive to climate change than previously thought with clear implications for its future behaviour.
“Our study reveals startling insight into just how responsive the Greenland ice sheet is to climate change. That it abruptly retreated to a configuration much smaller than present under levels of Arctic warming on a par with that ongoing today is a bleak reminder of its future committed loss to global sea-level rise and flooding. The ultimate irony”, says co-author Alun Hubbard from Oulu University, Finland, “is that as it retreats, the ice sheet itself adds to those emissions.”
At the moment, the amount of CH4 exported and released into the atmosphere is relatively small and not significant globally. However, that can change in the near future with the accelerating deglaciation.
“Our findings highlight the role of these recent ice margin fluctuations on subglacial carbon cycling. Despite the relatively small CH4 export from the GrIS at present, our results are highly relevant for the global CH4 budget assessments. Increased ice sheet melting will lead to greater subglacial connectivity and potentially amplified CH4 transport in the future, not only from the GrIS but also from the Antarctic Ice Sheet, where the organic matter reserves are much larger than in the Arctic”, says Jade Hatton, one of the lead authors of the study.
The findings are published in Nature Geoscience.
The research was supported by the Czech Ministry of Education as part of the ERC-CZ programme (project LL2004 ‘MARCH4G’ to Marek Stibal).
Hatton JE, Stehrer-Polášková A, Píka PA, Garnett MH, Klímová P, Wentzel LCP, Žárský JD, Trubač J, Arndt S, Hubbard A, Yde JC, Hawkings JR, Doting E, Murphy JG, Lamarche-Gagnon G, Wadham JL, Sapper SE, Christiansen JR, Jorgensen CJ, Stibal M (2026) Mid-Holocene retreat of the Greenland Ice Sheet indicated by subglacial methane release Nature Geoscience doi:10.1038/s41561-026-01976-5.
