Damn the dams?

Floodwaters from the Xiol

Are dams good, or is coal better or is nuclear the best option? You are sure to hear proponents of each espousing the respective energy option. What is the truth? Does it as always lie somewhere in between?

To reduce its carbon intensity by 40 percent by 2020, China has undertaken a five year plan with grandiose plans, among which are big dams. As part of its low-carbon diet, the Chinese government plans to approve new hydropower plants with a capacity of 140 gigawatts over the next five years. For comparison, Brazil, the United States and Canada have each built between 75 and 85 gigawatts of hydropower capacity in their entire history. Achieving the new plan's target would require building cascades of dams on several rivers in China's south-west and on the Tibetan plateau.

Experts believe this would spell disaster for its rivers and biodiversity hotspots. Because of dam building and other factors, freshwater species have on average lost half their populations between 1970 and 2000, and more than a third of all freshwater fishes are at risk of extinction.

International pressure to limit greenhouse gas emissions is the single most important factor behind the huge push for hydropower in China. But, in the process is it set to create new crises? Should emissions reductions come at the cost of biodiversity and loss of rivers?