Lakes and freshwater systems account for over 20% of all methane emissions into the atmosphere – much more than previously estimated, according to scientists at the University of Geneva (UNIGE). Until recently, it had been thought that methane could only be produced in oxygen-deprived environments, such as the sedimentary layers found at the bottom of lakes. In reality, surface water, even though it is mixed by the wind and rich in oxygen, produces a significant amount of methane, the group of researchers has revealed. This phenomenon, which is still largely unknown, has been highlighted by a two-year field study designed to measure the methane concentration and production in the surface water (the top five metres) of Lake Hallwil in canton Aargau. The UNIGE research, which is published in Nature Communications, shows that lakes play a critical role in the methane gas cycle, where the greenhouse effect is 28 times higher than for carbon dioxide. The measurement campaign was ...
