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Hotter Utah — not all bad?

A rising Great Salt Lake, a shrinking mountain snowpack and cutthroat trout that can't find streams cold enough to swim in — these are some of the possibilities if Utah's temperatures keep getting hotter, says Fred Wagner.

But there are some occasional pluses to global warming, Wagner told a climate change symposium this week at the Utah Department of Environmental Quality. The meeting of the Governor's Blue Ribbon Council on Climate Change is aimed at developing state policies to document and reduce greenhouse gas emissions in Utah.

Predicted rising temperatures and rising precipitation levels could also mean a longer growing season for farmers and longer grazing season for ranchers, said Wagner, professor emeritus of wildland resources at Utah State University.

When it comes to the study of climate — with its solar cycles and Pacific decadal oscillation and anthropogenic forcing — nothing is simple, as the past week's symposium underscored. The people who study climate change look both at what has already happened and at computer models of what might happen in the future.

Already, says Wagner, Utah has seen a mean annual temperature increase of 3 degrees Fahrenheit between 1894 and 2004 (much of that increase coming in nighttime temperatures) and an increase in precipitation of 14 percent during that same period. Or, as Wagner puts it, "the wet years are getting wetter and the dry years are not quite as dry."

Despite all that wetness and because of the increased temperatures, in the late fall and late spring, Utah's mountains are getting more rain than snow, and the rain is going immediately into the ground rather than into a snowpack that could turn into spring runoff to provide enough water for lawns and farms. On the other hand, increased precipitation could offset the runoff problem.

Data run by the National Center for Atmospheric Research in Boulder for a nine-state region that includes Utah showed that if carbon dioxide emissions double (a typical prediction), this will mean an increase in annual temperatures of between 6.5 and 11.7 degrees F (depending on who's doing the calculating) by the end of this century. It will also mean an increase in precipitation of at least 54 percent and possibly as much as 184 percent.

That poses significant questions of whether Utah's dams, reservoirs and aqueducts will be able to contain all that water, Wagner said. Considering a 12 percent rise in precipitation in the 20 years prior to the 1980s flooding of the Great Salt Lake that threatened I-80 and the airport, the projections mean that "the Wasatch Front will be in a heap of trouble."

Caspar Ammann, a climate scientist working at the National Center for Atmospheric Research, also spoke at the symposium, providing graph after graph of colored lines that pointed to bad news. "What-if" scenarios, he said, show even if the world stabilizes greenhouse emissions right now, the world would still warm up a fraction of a degree. If we keep on with "business almost as usual," temperatures will rise 8 degrees Fahrenheit by the end of the 21st century, he said.

The result, he says, will be "of a magnitude we haven't seen before." He reiterated the conclusion drawn earlier this year in Paris by the Intergovernmental Panel on Climate Change that it is "very unlikely" that global climate change of the past 50 years can be explained by natural causes alone.

Rising temperatures can mean "the potential for re-assortment of species," said USU's Wagner, who acknowledged that all this is "incredibly complex and is nothing that can be predicted at this point in time." But already, he said, scientists are observing that the phenology of plants and animals — when they bloom, reproduce, migrate — is changing. Robins in the Rocky Mountains, for example, are now migrating back 10 to 15 days earlier in the spring than they did 30 years ago.

Some species, like a variety of checkerspot butterfly, have been moving north. The red fox has moved farther north into Canada, putting it in conflict with the Arctic fox. The mountain pine beetle has moved north into British Columbia, decimating lodgepole pines there. Scientists are concerned that when the pine beetle moves into other new areas it will jump to other types of pines.

Rising air temperatures also increase the temperature of bodies of water, from oceans to streams. In Utah, that means that cutthroat trout, which prefer low-temperature waters, will move upstream, until they might eventually run out of water cold enough to live in, he said.