Rivers Losing Water Due to Climate Change

The Colorado River, the Yellow River in northern China, the Ganges in India and the Niger in West Africa are losing water, in some cases because of the effects of climate change, a new study finds.

The study examined stream flow in 925 of Earth's largest rivers, and found significant change in about one third of them over the past 50 years. These rivers, all key sources of water for the regions they flow through, were found to be funneling less water through their channels.

"Reduced runoff is increasing the pressure on freshwater resources in much of the world, especially with more demand for water as population increases," said lead author of the study, Aiguo Dai of the National Center for Atmospheric Research innew study instead appeared to be connected to climate change in many cases.

Climate change's influence on river flow comes through its effects on precipitation and evaporation. The authors compared the river discharge changes to previous studies that looked at changes in precipitation and found that areas of decreased discharge matched closely with areas of decreased precipitation (likewise, areas of increased discharge matched those of increased precipitation).

In the United States, for example, the Columbia River's flow declined by about 14 percent over the 50-year period, largely because of reduced precipitation and higher water usage in the West. The Mississippi River, on the other hand, had an increase in flow of 22 percent over the same period because of greater precipitation across the Midwest.

"As climate change inevitably continues in coming