Twenty-five percent more methane is being released from reservoirs than previously thought, according to a study published in BioScience, October 5, 2016. “The construction and operation of over 1 million dams globally (Lehner et al. 2011) has provided a variety of services important to a growing human population (e.g., hydropower, flood control, navigation, and water supply), but has also significantly altered water, nutrient, and ecosystem dynamics and fluxes in river networks… Artificial reservoirs created by dams are distinct from natural systems in a number of key ways that may enhance GHG emissions from these systems.” This is especially critical because of the recent boom in hydroelectric dam construction globally.
According to a study in Aquatic Sciences, January 2015, “ At least 3,700 major dams, each with a capacity of more than 1 MW, are either planned or under construction, primarily in countries with emerging economies. These dams are predicted to increase the present global hydroelectricity capacity by 73 % to about 1,700 GW.” The authors caution, “…,there is an urgent need to evaluate and to mitigate the social, economic, and ecological ramifications of the current boom in global dam construction”.