Atop Mount Graham, the squirrels' predicament is readily visible. Mixed conifers are replacing Douglas firs at higher altitudes, and recent fires have destroyed other parts of the forest, depriving the animals of the cones they need.
Environmentalists such as Turner worry about the disappearance of the Mount Graham squirrel, the long-tailed, mouselike vole and native wet meadows known as cienegas, but many lawmakers and state officials are more focused on the practical question of water supply.
Reese Woodling, in white, used to own a 2,700-acre ranch, but lack of rain reduced the grassland -- his main source of cattle feed.
Arizona gets its water from groundwater and rivers such as the massive Colorado, a 1,450-mile waterway that supplies water to seven states: Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming.
The recent drought and changing weather patterns have shrunk the western snowpack and drained the region's two biggest reservoirs, lakes Mead and Powell, to half their capacity. More precipitation is falling as rain instead of snow, and it is coming earlier in the year, which leads to rapid runoff that disappears quickly.
Scientists at Scripps Institution of Oceanography predict that by 2090 global warming will reduce the Sierra Nevada snowpack, which accounts for half of California's water reserves, by 30 percent to 90 percent.
"It makes water management more challenging," said Kathy Jacobs, who spent two decades managing state water resources before joining the University of Arizona's Water Resources Research Center. "You can either reduce demand or increase supply."
Water managers have just begun to consider climate change in their long-term planning. Forest managers have also started asking for climate briefings, now that scientists have documented that short, wet periods followed by drought lead to the kind of giant forest fires that have been devastating the West.
This month, scientists at the National Center for Atmospheric Research in Boulder, Colo., published a study showing that worldwide, regions suffering from serious drought more than doubled in area from the early 1970s to the early 2000s, with much of the change attributed to global warming. A separate recent report in the journal Science concluded that higher temperatures could cause serious long-term drought over western North America.
C. Mark Eakin, a paleoclimatologist at the National Oceanic and Atmospheric Administration who co-wrote the study in Science, said historical climate records suggest the current drought could just be the beginning.
"When you've got an increased tendency toward drought in a region that's already stressed, then you're just looking for trouble," Eakin said. "Weather is like rolling the dice, and climate change is like loading the dice."
Still, Arizona politicians remain divided on how to address global warming. Sen. John McCain (R-Ariz.) has led the national fight to impose mandatory limits on industrial carbon dioxide emissions that are linked to warming, though his bill remains stalled.
"We'll win on this issue because the evidence continues to accumulate," McCain said in an interview. "The question is how much damage will be done until we do prevail."
But other Arizona Republicans are resistant. State Sen. Robert Blendu, who opposed a bill last year to establish a climate change study committee, said he wants to make sure politicians "avoid the public knee-jerk reaction before we get sound science."
That mind-set frustrates ranchers such as Woodling, who is raising 10 grass-fed cows on a leased pasture. At age 69, he will never be able to rebuild his herd, he said, but he believes politicians have an obligation to help restore the environment.
"Man has been a great cause of this, and man needs to address it," he said.