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It turns out that humanity does not have the monopoly of self-destructive behavior.
A new study reports that an Icelandic glacier emits large amounts of methane, a potent greenhouse gas. The Sólheimajökull glacier – which comes from the active and ice-covered Katla volcano – generates and releases about 41 tons of methane (through the melt water) every day during the summer months. That's roughly equivalent to the methane produced by 136,000 cows, the team adds.
Melthane
"There is a huge amount of methane lost in the atmosphere by the flux of glacial meltwater," said Dr. Peter Wynn, Glacial Biogeochemist at the Center. Lancaster environment and corresponding author of the study.
"It largely exceeds the average losses of methane in the atmosphere by non-glacial rivers reported in the scientific literature. It rivals some of the most methane-producing wetlands in the world; and represents more than twenty times the known methane emissions of all the other volcanoes in Europe combined. "
Methane is a much more potent greenhouse gas than carbon dioxide (CO2) – 28 times more powerful, to be exact. It is therefore very important to know exactly how much it enters the atmosphere, both from an environmental and legal point of view (for cap-and-trade systems or similar systems).
Whether or not glaciers release methane has been debated. On the one hand, they are almost perfectly suited to the task: they combine organic matter, water and microbes under conditions of lack of oxygen (all very conducive to methane), covering them all of a thick layer of ice to trap gas. On the other hand, no one had ever checked to be sure. The team decided to take care of the issue in their own laboratories.
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They visited the Sólheimajökull glacier in Iceland to collect samples of the melt lake that it forms. The team then measured methane concentrations in the samples and compared them with methane levels in nearby sediments and other rivers to ensure that they did not take into account methane emissions in the sample. environment of the surrounding areas.
"The highest concentrations were found at the point where the river flows under the glacier and enters the lake. This shows that methane must come from below the glacier, "says Dr. Wynn.
Subsequent spectrometric analyzes revealed that methane was generated by microbial activity under the glacier. However, the volcano also has a role to play here. It does not generate methane directly, but "provides the conditions that allow microbes to grow and release methane into the surrounding melting waters," says Dr. Wynn.
The fact is that methane really likes oxygen. In fact, he loves so much that every time they meet, they connect to CO2. What usually happens with glaciers is that oxygen rich meltwater seeps into the bottom and convert the trapped methane into CO2. In Sólheimajökull, however, most of the oxygen from this melting water is neutralized by the gases produced by the Katla volcano. Methane remains unchanged, dissolves in water and escapes from below the glacier.
"Understanding the seasonal evolution of the subglacial drainage system of Sólheimajökull and its interaction with the Katla geothermal area was part of this work," said Professor Fiona Tweed, expert in glacial hydrology at Staffordshire University and co-ordinator. – author of the study.
Katla's heat also keeps the environment comfortable for microbes living under the glacier and can 'dramatically accelerate the generation of microbial methane. So you can see Katla as a giant microbial incubator, "says Dr. Hugh Tuffen, a volcanologist in Lancaster. University and co-author of the study.
These volcanoes and geothermies, linked to ice, are abundant in Iceland and Antarctica. This paper suggests that these systems can have a significant impact on our climate projections. Katla "emits huge amounts of CO2 – it's one of the top five in the world in terms of CO2 emissions from volcanoes," says Dr. Tuffen.
"If the methane produced under these ice caps has a way to escape as the ice dissipates, we may see a short-term increase in methane release from ice masses in the future." Says Dr. Rebecca Burns, lead author.
However, the team believes that it is not yet clear that such processes will take place in the context of climate change. There may be a short-term peak of methane released during melting glaciers, but the process could be self-limiting in the long term: without ice, methane production conditions would be eliminated.
The document "Direct Isotopic Evidence of Biogenic Methane Production and Temperate Glacial Effluent" was published in the journal Scientific reports.
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