Eutrophication will increase methane emissions from lakes and impoundments during the 21st century

Lakes and impoundments are an important source of methane (CH₄), a potent greenhouse gas, to the atmosphere. A recent analysis shows aquatic productivity (i.e., eutrophication) is an important driver of CH₄ emissions from lentic waters. Considering that aquatic productivity will increase over the next century due to climate change and a growing human population, a concomitant increase in aquatic CH₄ emissions may occur. We simulate the eutrophication of lentic waters under scenarios of future nutrient loading to inland waters and show that enhanced eutrophication of lakes and impoundments will substantially increase CH₄ emissions from these systems (+30-90%) over the next century. This increased CH₄ emission has an atmospheric impact of 1.7-2.6 Pg C-CO₂-eq y^-1, which is equivalent to 18-33% of annual CO₂ emissions from burning fossil fuels. Thus, it is not only important to limit eutrophication to preserve fragile water supplies, but also to avoid acceleration of climate change.