Scientists Just Confirmed A Key New Source Of Greenhouse Gases

In a forthcoming paper, scientists say anaerobic decomposition of sediement and other organic material inundated by reservoirs emits a significant amount of greenhouse gases, mainly methane.

"Countries around the world are trying to get their greenhouse gas emissions under control — to see them inch down, percentage point by percentage point, from where they stood earlier in the century. If everybody gets on board, and shaves off enough of those percentage points, we just might be able to get on a trajectory to keep the world from warming more than 2 degrees Celsius above the temperature where it stood prior to industrialization.

But if a new study is correct, there’s a big problem: There might be more greenhouse gases going into the atmosphere than we thought. That would mean an even larger need to cut.

The new paper, slated to be published next week in BioScience, confirms a  significant volume of greenhouse gas emissions coming from a little-considered place: Man-made reservoirs, held behind some 1 million dams around the world and created for the purposes of electricity generation, irrigation, and other human needs. In the study, 10 authors from U.S., Canadian, Chinese, Brazilian, and Dutch universities and institutions have synthesized a considerable body of prior research on the subject to conclude that these reservoirs may be emitting just shy of a gigaton, or billion tons, of annual carbon dioxide equivalents. That would mean they contributed 1.3 percent of the global total."

Chris Mooney reports for the Washington Post September 28, 2016.