This story is part of a special National Geographic News series on global water issues.
A new interactive Google Earth video tour aims to teach people how damming rivers around the world can exacerbate climate change.
The video, created by the nonprofit conservation groups International Rivers and Friends of the Earth International, is narrated by Nigerian environmental activist Nnimmo Bassey and will debut at the United Nations COP 17 Climate Change Conference in Durban, South Africa, this week.
"A lot of analyses of large dams have focused on their social and environmental impacts," said Zachary Hurwitz, policy coordinator for International Rivers. "In addition, greater attention needs to be paid to whether hydropower is a viable option in a warming climate," he said.
The approximately 12-minute video uses computer animation to simulate the potential climate hazards associated with building dams in Africa, the Himalayas, and the Amazon.
For example, the tour illustrates how glacier melt in the Himalayas, driven by global warming, could lead to higher flood and safety risks for communities living downstream from dams.
"So many dams are planned for Himalayan rivers that one dam burst could result in a domino effect of dam failure, putting millions of people at risk," Bassey says in the video.
In another section of the video tour, viewers are virtually plunged into the waters of Brazil's Tucurui Dam to see how rotting organic material at the bottom of the reservoir creates the greenhouse gas methane, which bubbles up and is released into the atmosphere.
The video will be released in two formats: a non-interactive version that will be available for viewing on YouTube, and a KML file that can be opened using free Google Earth software. In the KML version of the tour, users can pause at any point and zoom in and explore additional information and imagery about a topic.
Dams and Climate
Dam builders have argued that large dams are effective counters to climate change because they store water for energy production and irrigation in a warming and increasingly water-scarce world, International Rivers' Hurwitz said.
But conservation groups say that the plans for many large dams are based on historical river flow data that are irrelevant in today's rapidly changing and unpredictable climate.
"Large dams have always been based on the assumption that future stream-flow patterns will mirror those of the past, but this is no longer true," Rudo Sanyanga, International Rivers' African program director, said in a statement.
In the video, various alternatives to large dam projects are proposed. For example, solar and geothermal energy would be better methods for producing power in Africa, where millions of people live far from the electric grid. And in India, Bassey says, where the transmission system experiences some of the highest energy losses in the world, money could be better spent on creating a smarter, more efficient electric grid.
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David Tryse is a developer based in Dublin, Ireland, who has helped create numerous Google Earth applications for scientists and conservation groups, including International Rivers.
Tryse said he is excited about using Google Earth as a tool, because it gives hundreds of millions of people access to high-resolution satellite imagery and allows them to investigate environmental issues themselves.
"If a logging company claims there is no deforestation next to an important national park, then anyone can 'fly in' to verify this," Tryse, who helped develop the new dam video, said in an email.
Rhett Butler, the founder and editor of the environmental science and conservation news site Mongabay.com, said the video "really shows the scale of the dam issue."
"Before Google Earth, there was really not a good way to do this," said Butler, who was not involved in the project. "It's a very powerful way to convey a story. Maybe you would have had satellite pictures, but I'm sure the process would have been a lot more costly. Google Earth has made it a lot easier."
International Rivers says it hopes the new video will encourage the public to think about global dam issues and to contact their local lawmakers and other officials about their concerns.
"Large dams are not the silver bullet answer to climate change," Hurwitz said. "Climate policymakers at the UNFCCC [United Nations Framework Convention on Climate Change, COP 17] and the World Bank should support more decentralized and efficient water and energy solutions to meet the needs of developing countries," he said.