New study reports Greenland is a methane sink rather than a source

Researchers from the University of Copenhagen concluded that methane uptake in dry landscapes exceeds methane emissions from wetlands in the ice-free part of Greenland. The results of the new study provide important insights to climate models. Researchers are currently investigating whether the same results apply to other polar regions.

It has long been thought that the Arctic could be a ticking climate bomb. As local temperatures rise and permafrost melts, more methane, a greenhouse gas, is released. But in a new study from the Department of Geosciences and Natural Resource Management at the University of Copenhagen, researchers were able to conclude that at least Greenland does not appear to be a methane bomb after all.

In fact, Greenland consumes more methane than it releases, according to analyzes of soil samples from 11 regions of Greenland. The researchers used an existing dynamic methane model, which made it possible to quantify the methane balance for the whole of Greenland.

The researchers concluded that on average since 2000, the dry landscapes of ice-free Greenland have consumed more than 65,000 tonnes of methane from the atmosphere each year, while 9,000 tonnes of methane have been released each year from the humid atmosphere. areas.

“This is partly due to Greenland’s vast dry landscapes, where methane from the atmosphere is consumed in the upper layers of the soil, and partly because the ice-free regions of Greenland have only been ice-free “They have stored a lot of carbon, which could lead to significant methane emissions, as can be measured elsewhere in the Arctic,” explains the professor. Bo Elberling, who led the study.

The research is published in the journal Earth and Environment Communications.

Microorganisms make methane absorption possible

Methane absorption is made possible by a unique group of microorganisms that typically live in the top half meter of Arctic soil, where it is dry and oxygen is present. These microorganisms use methane that enters the ground from the atmosphere and transform it into carbon dioxide.

Although carbon dioxide is also a well-known greenhouse gas, its greenhouse effect is much weaker than that of methane, making the conversion of methane to carbon dioxide good news for the climate.

The study also provides knowledge on optimal soil conditions for methane absorption in the Arctic. This is because microorganisms need various nutrients and soil with just the right acidity (pH level).

Researcher and first author of the article Ludovica D’Imperio explains: “Our work also highlights the conditions which, in addition to climate, are crucial for the absorption of methane in Greenland. Based on our statistical model, we can conclude that it depends on the presence of the right microorganisms, soil acidity and copper, knowledge of which we were not sure before.

Greenland’s methane balance

Overall, the new study demonstrates that Greenland contributes low methane uptake under current conditions, which will most likely increase as Greenland’s climate changes in the future.

However, the conclusion is not that Greenland will have an impact on the total amount of atmospheric methane globally or that it will prove decisive for methane budgets in the Arctic. Greenland’s methane uptake is simply too low compared to other known methane sources, both in the Arctic and globally.

Indeed, the majority of Arctic wetlands, and therefore the largest natural source of methane, are found in Siberia. Until the outbreak of war between Russia and Ukraine, Danish researchers carried out studies there alongside their German and Dutch counterparts.

“We have just succeeded in demonstrating that methane uptake also occurs in dry soils in Siberia, but further studies will be needed in Siberia to provide a methane budget similar to what we currently have for Greenland. Nevertheless, We have made considerable progress with similar studies in Siberia, for example, in the cold regions of Tibet, where the measurements reach a similar conclusion to that in Greenland.

“But work is only just beginning to understand the variation in this methane uptake and its importance for the global methane budget,” says Elberling.

According to the researchers, the new study does not change the fact that greenhouse gas emissions from human activities must continue to be reduced. But the study brings previously unknown nuances to Greenland’s natural methane balance.

“Our research and that of others in the field is helping to increase our understanding of the complex processes that are critical to the global methane budget. The budgets will be used now and in the future to develop models that can provide a more comprehensive picture highlights the importance of global methane absorption,” concludes Bo Elberling.