How Might Global Climate Change Affect Life on Earth?
ESU501  Water Resource Impacts

Water is a critical resource for humans as well as other ecosystems. The water cycle is likely to be altered by climate change. Because of the complexity of the hydrosphere in the Earth system, it is difficult to predict how precipitation patterns might change. Changes expected include the timing, amount, and location of precipitation and runoff. Such changes will alter patterns of water availability and quality.

NASA
Image of the lower Colorado River taken from a space shuttle, showing how the river is completely used up before reaching the Gulf of California.

Example

The Colorado River Basin is extremely sensitive to climate change. A temperature increase of 2 degrees Celsius is estimated to reduce runoff by 4 to 12 percent. A 4 degree increase might reduce runoff by 10 to 20 percent. Increased temperature will decrease winter snowfall and accelerate spring snowmelt. As the Colorado River is used by people in seven states and two countries, even small decreases in runoff could have dramatic effects on human systems.

Effects of Climate Change on the Colorado River (EPA)

Water Links

US Global Change Research Program: Water Impacts

United Nations Framework Convention on Climate Change: Water Resources