In this month’s “In Depth,” we discuss the latest Antarctic campaign by the ICM and IGME, which has, for the first time, identified large methane gas leaks on the seabed, where it is stored in the form of solid crystalline structures.
Researchers from the Institut de Ciències del Mar (ICM-CSIC) and the Spanish Geological and Mining Institute (IGME-CSIC) returned on 17 February from Antarctica, where they witnessed a phenomenon previously unexplored at these latitudes: the release of large amounts of methane in a gaseous state from the seabed, where it is stored in the form of solid crystalline structures measuring up to 700 metres in length and 70 metres in width.
This discovery, which could reshape our understanding of the global carbon cycle and its impact on climate change, took place as part of an oceanographic campaign conducted aboard the research vessel Sarmiento de Gamboa within the ICEFLAME project. This initiative, led by the ICM and IGME, involved collaboration with the Free University of Brussels (Belgium) and the National Institute of Oceanography and Experimental Geophysics (Italy).
Roger Urgeles Esclasans, the campaign’s chief scientist and a researcher at the Seafloor and Sub-seafloor Processes Laboratory of the ICM, was accompanied by eight other members of the centre.
“We already knew about the existence of solid methane hydrates beneath the continental margins of the Antarctic Peninsula, but thanks to this campaign, we have been able to confirm our hypothesis of their gaseous dissociation. Some of these gas emissions rise from previously known faults, while others emerge from ones we have identified for the first time,” the expert explains.
A delicate balance
Methane hydrates depend on a fragile equilibrium of pressure and temperature. Since the last glacial maximum, around 20,000 years ago, Antarctica has been losing mass, causing the continent to rise and reducing pressure on the seabed. In this context, hydrates may dissociate, releasing methane in gaseous form. But is this a natural and stable process, or are we witnessing a phenomenon accelerated by global warming?
The answer to this question is crucial. Methane is a greenhouse gas (GHG) with a warming potential between 20 and 40 times greater than that of CO₂. If these emissions reach the atmosphere, they could contribute to global warming in a way not yet fully accounted for in climate models.
“We want to determine whether the dissociation of hydrates is a process in equilibrium with its surroundings or if it is being altered by external factors,” Urgeles warns.
To solve this mystery, the scientific team collected sediment, water, and gas samples at various depths. Additionally, by using acoustic probes, they have been able to map the geological structures housing the hydrates, revealing methane escape pathways. Now, a critical phase begins in the laboratory: meticulously analysing this data to model the evolution of hydrates and assess their future stability.
However, the team is not starting from scratch. There are existing time-series datasets on sea level, atmospheric temperature, and the amount of ice in Antarctica—parameters that influence the stability of the hydrates. Thanks to this data and the Antarctic Treaty’s open-data policy, scientists were able to previously map the hydrates and estimate the amount of methane they contain. “Without this possibility, we would not have been able to go straight to the right location during this campaign,” the geologist acknowledges.
Previous studies in the Arctic
The existence of methane hydrates in the oceanic subsoil has been known since the second half of the last century. We now know they are found in all oceans, predominantly beneath deep continental margins. The study of methane hydrates revolves around two main questions: the potential of these formations as a source of natural gas—primarily composed of methane—and their role as greenhouse gases contributing to global warming.
Additionally, in polar regions, ice retreat plays a crucial role, as it causes the continent to rise, making these deposits more dynamic than in other parts of the world. Until now, most studies had been conducted in the Arctic, particularly in relatively shallow waters where methane appears dissolved. However, in Antarctica, such emissions were almost entirely unknown until now.
This discovery does not only have climatic implications. When methane hydrate dissociates, it generates gaseous methane, which occupies much more space than its crystalline form. If the gas does not find “escape routes,” it can build up enough pressure to trigger submarine landslides of varying magnitudes. If large enough, these landslides could potentially cause tsunamis or earthquakes, but the team insists that it is too early to speculate on such possibilities in Antarctica.
Finally, ICEFLAME also includes a microbiological component, as another of its objectives is to understand how life adapts to the extreme conditions found in the fissures where methane escapes. There are microbial communities specialised in consuming this gas as an energy source. Understanding how these organisms respond to variations in methane flow could provide key insights into the stability of marine ecosystems in a warming world.
Geology in the media spotlight
The discovery of methane plumes in Antarctica has attracted significant media attention, both nationally and internationally, in recent weeks. Accustomed to geology rarely making headlines, Urgeles admits that “it’s a bit overwhelming to see this topic published in such widely circulated media,” and he confesses that in interviews, he has tried to communicate caution regarding the future findings, particularly those related to climate change.
Moreover, the first discoveries from this expedition have also reached social media. “I don’t have a social media account, but if you look at posts about this news, you’ll see not only a lot of comments but also all kinds of opinions. When you talk about climate, you realise that many people have poorly supported ideas and use language that can be quite shocking for a scientist,” the expert admits.
“That’s why, in recent interviews, I have tried to emphasise that, although we have detected methane emissions, it is too early to determine their exact origin and whether or not they are linked to human-induced climate change,” continues the geologist, who regrets that the media sometimes latch onto the most sensationalist words. “For example, a colleague said that this could be a ‘climate bomb,’ and the headlines were: ‘Climate bomb,’ which is an exaggeration,” he notes.
Although the potential climate effects remain uncertain, discovering these methane gas leaks from the depths of the Antarctic Ocean is already a significant contribution to our understanding of the dynamics of one of the most potent greenhouse gases. The retreat of ice in the poles is a reality, with consequences we do not yet fully understand, and this research aims to uncover some of them.