Farmers across the western half of the United States rely on snowmelt to irrigate their crops, but new research suggests snowmelt will become increasingly unreliable as Earth's climate continues to warm.

For the new study, published Monday in the journal Nature Climate Change, scientists looked at drainage basins that are heavily reliant on snowmelt runoff and face large irrigation water demands. Next, researchers used climate models to predict the effects of climate change on those basins.

The models -- which simulated the effects of temperature increases of 2 and 4 degrees Celsius, roughly 3.5 and 7 degrees Fahrenheit -- showed snowmelt-dependent basins will be at a heightened risk of scarcity. According to the data, the San Joaquin and Colorado river basins, both located in the American West, are two of the most likely to become overburdened in the coming decades.

"In many areas of the world, agriculture depends on snowmelt runoff happening at certain times and at certain magnitudes," Yue Qin, assistant professor of geography at Ohio State University, said in a news release. "But climate change is going to cause less snow and early melting in some basins, which could have profound effects on food production."

Without climate change, snowmelt meets 33 percent of the irrigation demand in the San Joaquin Basin. If the climate warms 4 degree Celsisus, that 33 percent will become 18 percent. Analysis suggests the Colorado River Basin will experience a similar drop off -- 38 percent to 23 percent.

The research suggests drainage basins in southern Europe, western China and Central Asia will also experience reduced snowmelt runoff supply. Increases in rainfall could offset losses in some parts of the world, but not in most.

"In many basins, future changes in rainfall do not compensate for the lost snowmelt in crops' growing seasons," said study co-author Nathaniel Mueller, an assistant professor at Colorado State University.

With less snowmelt runoff, farmers will have to turn to other water sources to meet their irrigation needs -- putting additional pressures on reservoirs and groundwater, sources that are already taxed. On a warming planet where prolonged droughts are expected to become more frequent, farmers won't be the only ones looking to new water sources to meet their needs.

These changes aren't going to happen overnight. Researchers hope their work can be used to help farmers and policymakers plan ahead in regions most at risk. Farmers in basins where water is likely to become increasingly scarce may need to put additional resources into developing drought-resilient crop varieties.

"We need to find ways to help those basins that will most need to adapt to the coming changes," Qin said.

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