Payal Parekh's picture
Payal Parekh
Former Climate Program Director
I put my scientific training into action as a weapon in the struggle against destructive river projects. I also work to debunk the myth that dams are good for the climate. We know that dams adversely impact a river's ability to adapt to climate change and dams in tropical regions can be major emitters of methane, a greenhouse gas that is 25 times more potent than carbon dioxide.

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Methane Emissions from Created Reservoirs

Fri, 10/16/2009 - 1:39pm
3Gorges Reservoir Sat (The Three Gorges Dam during construction viewed from a satellite in July 2003. Photo © European Space Agency (http://www.peopleandplanet.net/doc.php?id)

3Gorges Reservoir Sat (The Three Gorges Dam during construction viewed from a satellite in July 2003. Photo © European Space Agency (http://www.peopleandplanet.net/doc.php?id)

A new study that appeared in the Journal of Geophysical Research found that marshes created by the construction of the Three Gorges Dam emitted methane, a greenhouse gas twenty five times more potent than carbon dioxide. The emissions potential of created marshes hadn't been investigated until then.

This study reinforces that dams are emitters of methane and show the advantage that true renewables, such as solar and wind have over hydro.

Although the emissions from the Three Gorges Dam are low, emissions from created marshes could be higher in tropical zones. Therefore future budgets of greenhouse gas emissions from dams should also account for this newly identified source. Substantial research has shown that dam reservoirs and spillways are also sources of greenhouse gas emissions from dams.

It is encouraging that the Chinese Academy of Sciences supported this research. Approximately 50% of hydro reservoirs are located within China. Hopefully this study is a positive sign that China is willing to objectively investigate the climate and environmental impacts of its dams.