Large methane leaks discovered in Antarctica
A recently concluded expedition to the continental shelf of the Antarctic Peninsula, where methane hydrates are hidden in the seabed, revealed that the greenhouse gas methane escapes there.
Methane hydrates… Anyone who has read Frank Schätzing’s science fiction novel The Swarm from 2004 will be familiar with this term and may still know where they can be found and what consequences a sudden release could have.
These solid, crystalline structures occur in the ocean worldwide, especially along the deep continental slopes not too far from the coasts. Methane hydrates are hidden beneath the seabed and form in areas of low temperature and high pressure where microorganisms decompose organic material, releasing methane in the process – typically in water depths of around 200 to 300 meters in the polar regions and between 500 and 2,000 meters at lower latitudes.
Since methane hydrates stabilize continental slopes like cement, their release – due to rising temperatures rather than Schätzing’s intelligent swarm creatures, the “Yrr” – could have catastrophic effects such as underwater landslides and resulting tsunamis.
In addition, methane has a high climate impact, which is 20 to 40 times higher than that of carbon dioxide. If large quantities of the gas were released, this could contribute significantly to global warming – to an extent not yet taken into account by climate models.
Expedition for hidden methane
Most polar studies on methane hydrates have so far been carried out in the Arctic. To find out what the situation is with these structures in the Antarctic, a research team led by the Institut de Ciències del Mar (ICM-CSIC) and the Spanish Geological and Mining Institute (IGME-CSIC) undertook an expedition to the Antarctic Peninsula as part of the ICEFLAME project.
The researchers returned on February 17 and have now reported the discovery of large methane leaks on the sea floor in an ICM publication. For the first time, they were able to observe that large quantities of methane are released from the seabed in a gaseous state where methane hydrates occur.
“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,” explains Dr. Roger Urgeles, lead scientist of the research mission and researcher at ICM’s Seafloor and Sub-seafloor Processes Laboratory, in the institute’s article.
Is climate change accelerating methane emissions?
The research team now wants to find out whether the methane emissions are a natural and stable process or whether the fragile balance of pressure and temperature that holds the methane hydrates in the seabed is being shaken by climate change and accelerating the release.
Since the last glacial maximum around 20,000 years ago, the ice mass on the Antarctic continent has been shrinking – more recently at a much faster rate due to global warming. Due to the decreasing weight, the continent is rising and the pressure on the methane hydrates is decreasing.
“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 factorsors,” says Dr. Urgeles.
In the laboratory, the researchers are now analyzing the collected sediment, water and gas samples to learn more about the hydrates, model their development and assess their future stability.
The team is also investigating the microbiological communities around the methane leaks, which use the greenhouse gas as an energy source and thus “defuse” it or convert it into less climate-impacting carbon dioxide. The researchers hope that understanding the extent to which these communities respond to changes in methane concentrations could provide valuable insights into the stability of marine ecosystems in a warming world.
The significance of the discovery of methane emissions, particularly in relation to global warming, is still being investigated. Dr. Urgeles emphasizes that it is too early to determine their exact origin and the connection with man-made climate change. The team also considers speculation about scenarios of landslides and tsunamis in the Antarctic, as described by Frank Schätzing in his book, to be premature.
Julia Hager, Polar Journal AG
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