Melting Svalbard glaciers may flush ancient methane from rocks beneath the ice

Meltwater rivers from glaciers in Svalbard carry ancient methane from rocks beneath the ice into the atmosphere, according to new research published in Nature Communications. As the Arctic continues to warm, this feedback loop may worsen, releasing more powerful greenhouse gas methane. Gabrielle Kleber, a researcher at the iC3 Polar Research Hub in Tromsø, Norway, led the study, which analyzed 148 water samples from 19 glacier-fed rivers across central Svalbard.

Every river contained methane, with the highest levels reaching 425 times the expected atmospheric concentration. The methane is not produced by microbes under the ice but comes from the region's geology, particularly shale layers rich in organic carbon. When glaciers melt and form rivers, they interact with the rocks beneath, flushing methane out into the water.

The study found that glaciers with thawed, wet, and active beds are more effective at picking up methane, while those frozen to the bed are less connected to the underlying rocks. The research estimates that land-terminating glaciers in Svalbard may transport 182 to 368 tonnes of methane per year in meltwater, highlighting a widespread and undercounted pathway for ancient carbon to reach the atmosphere.