Dams cause immense loss of freshwater

London: Dams and irrigation considerably raise the global human consumption of freshwater by increasing evapotranspiration - an effect that increases the loss of freshwater to the atmosphere, thereby reducing the water available for humans, societies and ecosystems on land.

"Small things that we do on the surface of the Earth can have large global effects. Previously, the global effects of local human activities such as dams had been underestimated. This study shows that, so far, the effects are even greater than those from atmospheric climate change," said one of the researchers Fernando Jaramillo from Stockholm University in Sweden.

For the study, the researchers compiled and analysed data from 1901 to 2008 for climate, hydrology and water use in one hundred large hydrological basins spread over the world.