Climate models show that temperatures in California’s Sierra Nevada are expected to climb four degrees Celsius by 2100.
Those temperatures could lead to more tree and plant growth at higher elevations, which would suck up more water like a sponge.
The result is a 26 percent drop in water that would normally flow into rivers.
"We don’t really know how fast the vegetation can move up slope that’s probably the big, probably the biggest caveat of our analysis,” says Michael Goulden, a professor of Earth System Science and co-author of the study.
Goulden says the study is a worst-case scenario. It doesn’t take into account any future forest management that could change the extent of the problem.