Around the world, rivers seem to be flooding or shrinking. While Pasistan's rivers have left one-third of that country flooded and millions of people without homes, a drought unseen for 500 years has left Europe's major waterways almost dry. In the United States, the Kentucky River suffered deadly flooding this summer, while the Colorado River dropped sharply, which brought about water distribution cuts across several states.
There is little disagreement about what's going on. Scientists have warned for years that our changing climate will cause the frequency of both rainfall and droughts to increase, making the wet wetter and the dry drier, with more extreme impacts on rivers. The question now may be how to manage those waterways affected by climate change and, specifically, what role dams should or should not play in relieving the disasters we've been seeing lately and will see more of.
Advocates say water storage dams will become more significant which can stop water during flooding and allow it out in times of droughts. Dams, they say, can help relieve climate change by producing clean hydropower. "Dams and hydropower are fundamental to climate relief and adaptation," says Richard Taylor, a leading hydropower expert.
Not so. People holding opposite opinions claim that dams do more harm than good. Their arguments have long centered on the negative impact most dams have on biodiversity and river ecosystems, and increasing data show that dams actually worsen both floods and droughts. They also point out studies have shown that lakes created by dams often produce far more harmful greenhouse gases than people previously understood.
"Dams are thought to be a climate solution," says Isabella Winkler, who co-leads International Rivers, a U.S.-based advocacy group. "They have been praised as a source of green energy but they are actually not." Besides, scientists warn that many existing dams use operating rules based on old climate assumptions. New dams, experts agree, must be built for the worst cases.
