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Big wildfires are getting more frequent in Utah, a trend that follows broader patterns of rising temperatures and shrinking snowpack in spring.

A new analysis by Climate Central, a climate change think tank, shows big fires were much more common in the last decade than they were in the 1970s, when soil was generally wetter and temperatures were generally lower in springtime.

It is a pattern that is common all over the West, where the effects of climate change are more pronounced than in other parts of the nation, said Climate Central's Andrew Freedman.

"The story this tells us is not the complete story about wildfires in the West," he said, referring to population growth, firefighting practices and changing land-use patterns.

"But there are climate-driven relationships that are becoming clear," he added. "We wanted to show these relationships, to break them out."

Climate Central updated a report it produced last year and developed an interactive graphic that allows a comparison among Western states. It also charts, state by state, the upward trend of spring temperatures, April 1 moisture levels and 1,000-acre-plus wildfires over more than four decades.

The new analysis comes just days after burial of 19 members of a hotshot crew who were killed while battling the Yarnell Hill Fire in Arizona, the state seeing the West's most rapid increase in temperatures, according to Climate Central.

Utah State Forester Dick Buehler agrees "fires seem to be getting bigger than they use to" be. But he disagrees about the causes.

Cheatgrass and other invasive species in lower elevations and forest health in higher elevations are more important factors, he said. Healthy wildlands would be better able to withstand the heat and dryness, he said.

"But, if our landscapes were healthy," said Buehler, who has observed the changes firsthand since he began as a forester in 1973, "they'd be able to withstand those factors."

More than 250 fires already have erupted in Utah so far this year, the state forester added. Most were put out quickly, many of them tackled by local firefighting teams that were trained in tactics essential for battling wildland fires.

Like Freedman, Buehler noted that growing populations play a role in the wildfire trend, too. He pointed out that, when he started in the mid-'70s, Utah's population was around 1 million. Now it has more than doubled.

Meanwhile, about half of last year's fires were human-caused, he said.

"You have to throw that human factor in," he said.

Twitter: @judyfutah