Spencer K. Jones / Special to the Las Vegas Sun
Sunday, July 10, 2016 | 2 a.m.
Wildfire’s best friend
In fighting and preventing wildfires, Nevada officials often face a foreign obstacle: cheatgrass. Although the fast-burning invasive species is native to Eurasia, it has spread throughout the United States and particularly in the West. When it dries out in the summer, cheatgrass turns into a powerful fuel that amplifies the spread of fire. For years, researchers have worked on developing methods to eradicate the plant, but its presence remains an issue for fire responders in Nevada. This month, cheatgrass was credited for providing a portion of fuel for the Hot Pot Fire near Battle Mountain in Northern Nevada. The fire, which threatened homeowners and prompted evacuations, burned more than 120,000 acres.
A changing climate could increase the risk of large wildfires in states across the West, including Nevada, which has seen relatively mild wildfire activity in the past. That’s according to a report from nonprofit organization Climate Central, which expects Nevada will add 20 days of annual high wildfire potential by 2050, the fifth-largest increase among the 11 Western states included in the study.
Rising temperatures, increasingly parched landscapes and changes to the snowpack are contributing to the regional trend, argues the wildfire report released last month. The study, which pulled from U.S. Forest Service records and climate-change models, said fires in the West had increased in frequency and size since the 1970s. The overall season is now 105 days longer than it was then.
“The West has been seeing wildfires for a long time,” said Alyson Kenward, a co-author and a vice president at Climate Central. “What our analysis is showing is the threat is projected to increase even more.”
Changes in temperature matter because dry vegetation is more likely to ignite by lightning or human contact.
“In the spring and summer, hotter temperatures lead to drying of fire fuels — the duff and downed wood on the forest floor, and the standing trees,” the Climate Central report says.
Nevada has relatively few large fires compared with California or Arizona, but it’s poised for an increase in potential for wildfire and associated risks, the study says. Examining U.S. Forest Service data on fires larger than 1,000 acres, it shows that Nevada usually sees less than 10 per year, whereas California might see more than 20. However, the projected expansion of Nevada’s fire season means greater danger for about 46 percent of the population — 1.2 million people — living in areas at higher risk for fire. That includes places where residences or communities border or intermingle with the wilderness. Many are in Northern Nevada, such as the Reno foothills.
“Where (they) become problematic is when wildfires are burning where people are,” Kenward said. “What we are seeing here is that the number of wildfires in the West and in Nevada are increasing, while there are more and more people moving into areas where wildfires might burn.”
Although studies have shown changing temperatures and weather patterns affecting wildfires, experts say it’s difficult to anticipate the future because there are other variables at play.
Tim Brown, a Reno-based professor at the Desert Research Institute and a director of its Western Regional Climate Center, said that while higher temperatures might dry out more vegetation, increasing the fuel available for a fire, a lack of precipitation could discourage vegetation growth and decrease available fuel.
“It works both ways,” he said.
Regardless, Brown notes that increased temperatures and reduced precipitation have extended the fire season.
“Climate change is playing a role, but it’s not everything,” he said.
Like many Western states, Nevada faces an additional fire hazard due to the presence of cheatgrass, a fast-burning invasive species that amplifies a wildfire’s ability to spread.
Kenward said the Climate Central report drew its projections from several climate models, assuming rising temperatures based on a high-emission scenario for greenhouse gasses.
“If greenhouse-gas emissions continue unabated, these are the projections,” she said.
Mark Schwartz, director of the John Muir Institute of the Environment at UC-Davis, said attributing wildfire patterns to climate change alone was difficult, especially in the West. But if projections hold true, he said the drier and more variable weather patterns could support high-intensity fires that could alter ecosystems. What was once a forest might become an area populated by smaller vegetation, such as shrubs or grass.
“It’s suggesting that we are going to reset ecosystems in a big way,” Schwartz said.
But Nevada is unlikely to bear the worst of the damage from more severe wildfires. According to the Climate Central report, Arizona is predicted to add 34 high wildfire potential days. And in Colorado, changes in snow patterns have already left fuel drier and more vulnerable to fire.
“It is affecting and will continue to affect Nevada, but it is nowhere near the impact on the Pacific Northwest or the Northern Rockies,” said LeRoy Westerling, an associate professor at UC-Merced.