Global warming may increase methane emissions from freshwater ecosystems

A press release from the University of Exeter: New research led by the University of Exeter suggests that rising global temperatures will increase the quantity of the key greenhouse gas methane emitted from freshwater ecosystems to the Earth’s atmosphere – which could in turn lead to further warming.

The collaborative study, led by Dr Gabriel Yvon-Durocher from the University of Exeter, collated data from hundreds of laboratory experiments and field surveys to demonstrate that the speed at which methane fluxes increase with temperature was the same whether single species populations of methanogens, microbial communities or whole ecosystems were analyzed.

Dr Yvon-Durocher said: “This is important because biological methane fluxes are a major component of global methane emissions, but there is uncertainty about their magnitude and the factors that regulate them. This hinders our ability to predict the response of this key component of the carbon cycle to global warming. Our research provides scientists with an important clue about the mechanisms that may control the response of methane emissions from ecosystems to global warming.”

Methane is an important greenhouse gas because it has 25 times the global warming effect of carbon dioxide. The production of methane in freshwater ecosystems is brought about by an ancient group of microorganisms called Archaea that exist in waterlogged sediments where there is no oxygen. They play an important role in the decomposition of biomass, but rather than producing carbon dioxide, they produce methane as a by-product of their metabolism.

The report, published today in the leading scientific journal Nature, also showed that the temperature response of methane production is much higher than respiration (production of carbon dioxide) or photosynthesis (consumption of carbon dioxide), indicating that global warming may increase the amount of methanerelative to carbon dioxide emitted globally from aquatic ecosystems, terrestrial wetlands and rice paddies...

Archaeobacteria in a hot springs in Yellowstone National Park, shot by Wing-Chi Poon, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 2.5 Generic license