WASHINGTON - Wildfires have burned a record-breaking 1.25 million hectares in California as of Saturday. Washington state is enduring its second-largest area burned. A half-million people are under a fire evacuation warning or order in Oregon, one-tenth of the state's population.

The devastation is not unexpected. Climate experts have been sounding the alarm for a long time, said University of California, Merced, wildfire expert LeRoy Westerling.

"We've been doing modeling and simulations for years now that indicate that these really severe widespread fire seasons are coming, beyond anything that we've really experienced in the historical record," he said. "And we're seeing that emerge in real time, year by year here in California and around the western United States. So in that sense it's not surprising at all."

On the other hand, he added, living through it is another story. "It feels very real and very surprising every year as it ratchets up and gets a little more horrible."

Heating up, drying out

Wildfires need dry plants to burn, and climate change is helping increase the supply, Westerling said.

Higher temperatures mean flammable materials dry out faster. California and Oregon have already warmed about 1.1 degrees Celsius on average since the start of the 20th century, and Washington is about 0.8 degrees C warmer, according to the National Oceanic and Atmospheric Administration. High-temperature extremes are becoming more common, too, especially the number of warm nights.

The warming climate affects water supplies throughout the year. Mountain snowmelt is a critical long-lasting source of water in much of the region. But less precipitation is falling as snow and more as rain, which runs off faster. That means less water is available when the dry summer months arrive.

Those summers have been especially dry. According to a recent study, the Southwestern United States is the second-driest it has been in more than 1,000 years. Only the late 1500s were drier. While the region is dry to begin with, the study found that climate change has turned what would have been a moderate drought into a multidecade megadrought.

These conditions are punishing the West's forests. Not only has the drought killed millions of trees, it has made the rest more vulnerable to attack from beetle infestations. And the beetles are faring better in the warmer climate. More of them are surviving the milder winters. The result is nearly 150 million dead, flammable trees over nearly 4 million hectares in California alone in 2018, according to the U.S. Forest Service.

Human factors

Humans are making the situation worse in a number of ways.

Fire is a natural part of Western ecosystems. Fires would burn on the forest floor, clearing out vegetation between larger, fire-hardy trees. But for decades, residents and industries in the region have worked to tamp fires down as much as possible.

The forests have grown denser as a result, and also more vulnerable to drought, because the trees are competing for water, Westerling said.

When a fire breaks out, it can spread more easily from tree to tree, burning more intensely and more destructively than fires that burn on the forest floor, he noted.

Plus, a growing number of people are living in vulnerable areas near wilderness, raising the risk of loss of life and property.

And more people means more fires, whether from power lines, campfires, cigarettes, fireworks or, more rarely, arson.

More to come

And this is just the beginning.

A fire season like this one is "becoming more common, and it is projected to continue going in this direction" in the coming decades as climate change ratchets up, according to Erica Fleishman, director of the Oregon Climate Change Research Institute at Oregon State University.

Temperatures are expected to continue rising. Total annual precipitation might not change much, but it is expected to come in fewer, larger storms, she said.

Summers are predicted to be drier. "We already got very little (summer) precipitation, but we're expecting even less," said U.S. Department of Agriculture Northwest Climate Hub Director Jessica Halofsky.

Add to that the lessening snowpack, she said, and "there's going to be more fire in the Pacific Northwest, and a kind of ballpark (estimate) is maybe two to three times the annual area burned in the future than we've had in the past."

Predicted decades ago

With dozens missing in Oregon and at least 19 dead in California this year, Western officials are calling out the effects of climate change.

"This is not an act of God," Washington Gov. Jay Inslee said Friday. "This has happened because we have changed the climate of the state of Washington in dramatic ways."

"We're in the midst of a climate emergency," California Gov. Gavin Newsom said Friday. "We're experiencing what so many people predicted decades and decades ago. But all of that now is reality."

It's little comfort to the scientists who predicted it.

"It's really not satisfying being correct," Oregon State's Fleishman said. "You wish that you were not, in these cases, and it's heartbreaking."

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