American researchers have found that fluctuating water levels in dams and reservoirs emit large amount of greenhouse gases, the main culprits of global warming.
Researchers at Washington State University-Vancouver have documented the emission of greenhouse gases like methane, as water levels go up and down in dams and reservoirs.
Methane is 25 times more effective than carbon dioxide at trapping heat in the atmosphere. And while dams and the water behind them cover only a small portion of the earth's surface, they harbour biological activity that can produce large amounts of greenhouse gases.
"Reservoirs have typically been looked at as a green energy source. But their role in greenhouse gas emissions has been overlooked," researcher at Washington State University Bridget Deemer said.