Freshwater lakes in the northern hemisphere could double methane emissions over the next five decades, says a new study. Scientists have discovered that lakes could be triggered by warmer water, increasing the growth of aquatic plants and thus increasing the methane emissions. This issue is also known as “damaging feedback loop” in lakes.
An international team of researchers – from the University of Cambridge, Canada, and Germany, found that debris from trees can help suppress the methane production, but the plants inside the lakes (cattails, for example), can increase it.
The new study was published on 4 May in the journal Nature Communications. The senior author of the study is Dr. Andrew Tanentzap (University of Cambridge’s Department of Plant Sciences).
16% of the Natural Methane Emissions Produced By Lakes
Methane is, according to scientists, 25 times more powerful than carbon dioxide in the atmosphere. According to Dr. Andrew Tanentzap, freshwater ecosystems produce 16% of methane emissions on Earth, while the world’s oceans produce 1% methane.
Almost 77% of the methane emissions from lakes come from organic matter from plants that grow close or inside the water. The plants shed debris, which then microbes consume, generating methane through the surface of the water, into the atmosphere.
In their study, scientists used three kinds of plant debris to find out how methane emmisions vary: they used coniferous trees (debris: pine needles), deciduous trees (debris: leaves) and cattails.
Plants Increase the Emissions, But Only Because of Warmer Climates
Researchers incubated the samples for 150 days in the lab. Then, they analyzed the amount of methane generated by microbes in the sediments of the lake. They realized that the organic matter entering the lake is critical. Results showed that cattails produce over 400 times more methane than conifers and 2,800 times of methane produced by deciduous trees. Dr. Tanentzap explains the huge difference of emissions:
“The cattails don’t have the same chemicals, and so they are no longer inhibiting the microbes from producing methane.”
Plants like cattails in and around the lakes in the northern regions can grow with the rising temperature, thus producing more methane emissions. With climate impacting animals and plants lives, cattail could double in the next 50 years, increasing the production of methane.
Andre Blair s is the lead editor for Advocator.ca. He holds a B.A. in Psychology from the University of Toronto, and a Master of Science in Public Health (M.S.P.H.) from the School of Public Health, Department of Health Administration, at the University of North Carolina at Chapel Hill. Andre specializes in environmental health, but writes on a variety of issues.