Greenland meltwater may trigger methane “fire ice” release

Greenland meltwater – New research suggests glacial meltwater can flush methane hydrates beneath Greenland, potentially amplifying warming.

A warming world is starting to test a hidden fuel source under Greenland: methane trapped in ice-like deposits could be set loose as meltwater reshapes the seafloor beneath retreating glaciers.

Methane hydrates. sometimes nicknamed “fire ice. ” form when methane gas molecules become locked inside a cage of water molecules. creating a substance that is ice-like but still capable of burning.. They form in sediments where conditions are cold and under high pressure. including beneath the ocean. in permafrost regions. and under glaciers.. Some estimates have suggested these deposits contain enough carbon to rival the total stored in coal. oil. and conventional gas combined.

In recent decades, scientists have focused on how global warming disrupts the cold, pressurized environment that keeps hydrates stable.. One reason for that concern came from Arctic observations: a mysterious 50-metre-deep crater reported in the Russian Arctic in 2014 was linked in a 2024 study to permafrost thaw that suddenly reduced pressure on methane hydrates.. That mechanism, if correct, would have allowed methane to escape with violent force.

Now, researchers have identified a different pathway in Greenland, showing that meltwater itself can help unseal methane hydrates.. Led by Mads Huuse at the University of Manchester. the team reported evidence that water flowing from the ice sheet could flush hydrates that had previously seemed secure.

Huuse and colleagues focused on the seafloor of Melville Bay in north-western Greenland. where methane hydrates were known to be widespread between sediment grains.. Seismic surveys conducted by oil and gas companies in 2011 and 2013 revealed 50 large pockmarks in the seabed. some as deep as 37 metres. grouped near a long underwater feature called a grounding zone wedge.

During the last glacial maximum. this grounding zone wedge marked where the floating part of the Greenland ice sheet met the ocean bottom.. At first, the researchers suspected the pockmarks could have been carved by overturning icebergs.. But when they drilled sediment cores in the same area. the upper sediment layers showed little sign of methane. even though the temperature and pressure conditions indicated hydrates should have been stable there.

The drill results also revealed a crucial clue: large volumes of fresh water embedded in the sediments. not the seawater chemistry the team expected.. That signature pointed toward meltwater from the Greenland ice sheet.. The researchers concluded that. during the glacial maximum. meltwater moving beneath the glaciers into Melville Bay was pushed through the grounding zone wedge. flushing out methane hydrates along the way.

Looking ahead. the study’s findings suggest that similar grounding zone wedges across the Arctic could become pathways for hydrate release as glaciers retreat and meltwater routing changes.. In Huuse’s view. meltwater could wash out hydrates at the edges of other ice masses under climate change. effectively turning a once-stable reservoir into a moving target.

The study did not attempt to calculate exactly how much methane left Melville Bay. but Huuse estimated the release could have been on the order of 130 million tonnes.. He also noted that methane might have been released over a longer period than a simple snapshot implies. rather than as a short burst. and that the emission would have depended on how much methane dissolved in seawater before reaching the atmosphere.

That matters because methane released into ocean water does not automatically translate into equal amounts of atmospheric methane.. Depending on how saturated the surrounding seawater is. only a fraction of the gas may escape to the sky. with the rest potentially lingering in the ocean or undergoing transformation.

The Greenland findings arrive at a time when methane is already being measured under the ice sheet.. A study published this month reported that meltwater streams across western Greenland emit an estimated 715 tonnes of methane per year.. While some of that could involve hydrates. the lead researcher. Jade Hatton at the UK Centre for Ecology and Hydrology. argued that much of the methane is more likely coming from ancient plant material.. In that scenario. bacteria convert old organic carbon stored beneath or within the ice into methane. and enhanced melting would likely intensify that biological pathway.

Beyond Greenland, the stakes may extend much farther.. The Antarctic ice sheet is thought to sit atop even more methane hydrates than Greenland. with polar regions overall estimated to hold between 100 billion and 760 billion tonnes of methane in subglacial and marine hydrates.. Even releasing a fraction of those totals could rival methane emissions from Arctic and boreal biomes. which are largely driven by wetlands. lakes. and streams. and could accelerate climate change.

For climate researchers and policymakers. the central message is that hydrate stability may be more vulnerable than previously assumed—not only because of warming temperatures. but also because meltwater can reorganize physical pathways through sediments.. As ice sheets continue to shrink. the ability of meltwater to flush “fire ice” could become an important variable in forecasting how quickly trapped carbon could re-enter the atmosphere.

Greenland methane hydrates fire ice meltwater grounding zone wedge Arctic methane release climate change risk seismic pockmarks