Sizzling Future Predicted for Intermountain West

Sizzling Future Predicted for Intermountain West

More than 125 regional scientists and stakeholders analyzed ice-core and tree-ring data, historical weather records, climate patterns and levels of carbon dioxide to conclude what many have already decided: the West is getting hotter.

"Recorded temperatures since the middle of the nineteenth century show an abrupt rise, exceeding levels seen in the preceding thousand years," said Fred Wagner, Utah State University researcher and principal investigator for the nine-state Rocky Mountain/Great Basin region, part of a Congressionally mandated assessment of climate change on the United States.

"The data seems to indicate that gradually rising temperatures during the previous century will accelerate in this century due to increased levels of carbon dioxide in the atmosphere," Wagner said.

Whether the West will become dryer — or wetter — is still up for debate, and will require continued tracking. The region could see more precipitation, or more severe drought.

"We don't have enough data to predict with certainty," Wagner said.

According to the study, Great Basin and Rocky Mountain snow packs provide 85 percent of the surface water used by cities, industry, agriculture, recreation and hydropower. If drought patterns persist and spring runoff continues to decline, the Colorado, Rio Grande, Columbia, Missouri, Platte and Arkansas rivers could have distinctly reduced flows, leaving the region vulnerable to extreme water shortages. By 2070, according to the study, glacial snow packs in the West may disappear. Glaciers are already shrinking in Glacier National Park.

Water in the West is allocated on a first come first serve basis, with senior rights holders holding the trump cards. Junior holders could come up empty in coming years. The shortage is exacerbated by ground water that's being polluted and mined faster than it's being recharged, higher temperatures leading to massive evaporation in existing dams, and increasing demands by urban users, the report states.

Society may see the return of water disputes like those of the historical West, Wagner said.

"If the massive natural and human-made hydrology systems that sustain municipalities, farms and ecosystems were to see significant changes, there would be serious social, economic and ecological impacts," he said.

Northern and western areas in the nine-state region saw annual precipitation and river flows increase during the last century, with increases occurring mostly in early summer, the report stated. If this trend continues those areas could see severe flooding. A particularly vulnerable area is the heavily populated Wasatch Front in Utah. The nearby Great Salt Lake may rise to historic levels, causing extensive flooding. Arid southern states are seeing changes, too, with hotter, dryer conditions.

A burgeoning population, according to Wagner, compounds the problem. In recent decades the West has been the fastest growing region in the United States, filling up with new homes, heat-retaining blacktop and water guzzling lawns.

Whatever the future holds, scientists say, it will feature more extreme weather. That could wreck havoc for economies, natural ecosystems, agriculture and water management systems.

According to the study, insect outbreaks similar to those seen in the last several years may become more problematic. Continued drought would hasten the decline of communities based on livestock ranching. Some climatologists predict the disappearance of the ski industry and associated tourism. Dams could fail under the onslaught of heavy spring runoff or high flows.

Drought also leads to the invasion of cheatgrass and other non-native species on public lands, which fuels hotter, more frequent fires, said Wagner. Nevada has lost a fifth of its sagebrush to cheatgrass, and highly combustible fires may prevent its return.

"The north may see reduced snowpack, higher stream flows, increased flood potential and hotter fall, winter and spring temperatures," Wagner said. "In the south we could see snowpack elimination, reduced spring runoff and annual stream flows, increased evapotranspiration, and warmer winter and late summer temperatures."

More than 125 scientists and stakeholders participated in the regional fact-finding process, including researchers from the National Center for Atmospheric Research, the U.S. Bureau of Land Management, the Ecology Center and the Utah Water Research Laboratory at Utah State University, and the Midcontinent Ecological Science Center at Colorado State University. Members of water districts, farm bureaus, the ranching community, environmental groups, and tourism and outdoor recreation groups participated.

The nine-state study region includes Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming.

Contact: Fred Wagner, fwagner@cc.usu.edu, 435-797-2852
Writer: Nadene Steinhoff, nadene.steinhoff@usu.edu, (435) 797-1429