Unaccounted CO <sub>2</sub> leaks downstream of a large tropical hydroelectric reservoir
Elisa Calamita, Annunziato Siviglia, Gretchen M. Gettel, Mário J. Franca, R. Scott Winton, Cristian R. Teodoru, Martin Schmid, Bernhard Wehrli
Abstract
Significance Hydroelectric reservoirs emit substantial amounts of CO 2 , especially in the tropics. Since many such systems exist and many more will be built within decades, it is important to assess their role in the carbon cycle. A major source of emission that is rarely monitored and never at different timescales is the carbon released downstream of dams. We measured the seasonal and subdaily variability of CO 2 emission downstream of one of the world’s largest artificial reservoirs and find that its contribution is relevant for unbiased quantification of reservoir carbon budgets. These findings highlight the importance of subdaily variability in hydropower operation for downstream emission rates and call for appropriate analysis schemes to reassess the greenhouse gas footprint of this energy source.