The loss of rainforests in developing nations like Brazil means less hydroelectric power available.  So says a study from the US National Academy of Sciences.

Now, scientists have known for years that taking away the trees in the watersheds gives rainwater no place to go except down the river, and quickly to the oceans.  That’s resulted in a lot of landslides and flooding in places like America’s Pacific Northwest and California.

But in steamy rainforests, that’s eventually going to mean less rain.  Because rainwater will no longer be absorbed by the roots of trees that aren’t there.  The water in the soil, which would otherwise have been taken up by the tree roots and sent into the atmosphere, instead moves directly into streams and rivers. 

The entire cycle of rainfall, absorption, and release is broken: Large areas of tropical forest that used to create rain clouds, as moisture from their leaves evaporated are gone.  The elimination of swaths of these forests decreases rainfall.  Cut down enough trees, the scientists argue, and the indirect impact of lost rainfall outweighs the direct impact of removing trees.

The study warns that by 2050, projects like the Belo Monte Dam on the Xingu River will miss its generating goal of 4,400 megawatts by as 40 percent.  And the problem is hardly limited to Brazil; Central Africa, Indonesia, India, and other parts of the world could suffer as well.