Hydroelectric dams emit a billion tonnes of greenhouse gases a year, study finds | Global development | The Guardian
Hydroelectric dams contribute more to global warming than previously estimated, according to a study published in BioScience.
It appears that the current and planned boom of hydroelectric projects would double the current cover of dams in the world and will aggravate the problem.
Researchers found that rotting vegetation in the water means that the dams emit about a billion tonnes of greenhouse gases every year. This represents 1.3% of total annual anthropogenic (human-caused) global emissions.
When considered over a 100-year timescale, dams produce more methane than rice plantations and biomass burning, the study showed.
“We estimate that dams emit around 25% more methane by unit of surface than previously estimated,” said Bridget Deemer, from the School of Environment at the Washington State University in Vancouver, and lead author of the study.