New York Times: Fewer Rain Forests Mean Less Energy for Developing Nations, Study Finds
13 September 2013 The loss of tropical rain forests is likely to reduce the energy output of hydroelectric projects in countries like Brazil that are investing billions of dollars to create power to support economic growth.
That is the conclusion of a group of experts whose findings, released Monday, run counter to the conventional understanding of deforestation’s impact on watersheds.But the study warns that by 2050 as much as 40 percent of this power could be lost because of the reduced rainfall caused by regional deforestation.
Loss of tropical rain forests in the Amazon basin, Central Africa, Indonesia and other parts of the world has been a pressing environmental issue for two decades, but the debate has been framed largely in two ways. First, that the loss of the forests accelerates worldwide climate change be removing a large carbon sink that absorbs carbon dioxide from the atmosphere. Second, that the deforestation destroys the livelihoods of indigenous communities.
The idea that deforestation could reduce rainfall and thus economically harm a country like Brazil, which gets more than 80 percent of its energy from hydropower, is less familiar news.
Noting the established connection between the loss of trees and an increase in river flow, Claudia M. Stickler, the paper’s lead author, said researchers in the Amazon basin “saw effects where the conventional wisdom did not hold true.”
“They removed so much forest that it reduced rainfall and reduced the stream flow,” she added.
A co-author, Daniel C. Nepstad, who like Dr. Stickler works at the Amazon Institute for Environmental Research in Brasília, said rain forests create rain because they “are in the equatorial sun, evaporating a huge amount of water that goes up through the stems and into the leaves and out into the atmosphere.” That moisture feeds rain clouds.
In some eastern and southern tributaries of the Amazon, he added, “the cycle has changed.” The Xingu River, he said, is already near a tipping point where the increased flows caused by the loss of tree roots will be nullified by the overall loss of rainfall.
The authors concluded that “as tropical rain forest nations turn increasingly to hydropower to meet growing demands for ‘green’ electricity, it is important” that planners take into account the links between forest cover and stream flows.
