Global hydropower boom will add to climate change

From the Amazon Basin to boreal forests, and from the Mekong to the Himalayan foothills, rivers worldwide are being targeted for major new dams in a global hydropower boom that also aims to supply drinking water to exploding human populations and to facilitate navigation on the planet’s rivers; 3,700 new dams – 847 of them larger than 100 megawatts – are slated for construction. But one strong argument in favor of hydropower is now looking far weaker. Scientists have compiled the most comprehensive assessment yet of the global impact that dam reservoirs have on the world’s atmosphere and greenhouse emissions. And it isn’t good news. Globally, the researchers estimate that reservoirs – long considered “zero emitters” by the United Nations climate program – contribute 1.3% of man-made greenhouse gas emissions. Emissions on this scale are comparable to those from rice paddy cultivation or biomass burning, the study authors write.

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