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The death of 19 firefighters in Arizona this summer has focused attention on how bad wildfires had become in the West. Over the last decade, the region has experienced some of the worst fire seasons on record. In addition to lives lost, the disaster has cost billions for firefighting and destroyed property. And as NPR's Christopher Joyce reports, research suggests the situation is going to get worst.
CHRISTOPHER JOYCE, BYLINE: Ray Rasker is an economist who lives in fire country, southwestern Montana. At his company, Headwaters Economics, he tracks fire records the way other economists study business cycles or commodity prices. And he's seen a disturbing trend. First...
RAY RASKER: The fires are twice as large, they're burning twice as long, and the season is starting earlier and ending later.
JOYCE: Second, more homes are being built right next to national forests. When those forests burn, firefighters have to defend those homes. And Rasker notices that when it's unusually warm, things get worse. In Montana, when it's just one degree warmer than average, 35 percent more land burns. That costs money.
RASKER: The really striking thing is that when the average summertime temperature is just one degree Fahrenheit warmer, the cost of defending these homes doubles.
JOYCE: Rasker says these numbers are similar in California and Oregon too. He notes that about 84 percent of the private land around national forests is still open to development: housing developments and resorts and vacation homes.
RASKER: We're on a growth trajectory that is very scary. And, you know, if we think it's expensive and dangerous now, we're just now seeing the very beginnings of how big this problem is actually going to be very soon.
JOYCE: Already, the firefighting portion of the service's budget is higher than ever. David Cleaves is the service's climate and fire expert.
DAVID CLEAVES: In 2012, it was over 47 percent. Economically and in a policy sense, you could call it a crisis in the future.
JOYCE: A future crisis because as more money goes to firefighting, there's less for prevention. The service trims back or burns undergrowth and trees. And now it's letting some natural fires burn longer to get rid of built-up fuel. But service assistant fire manager Elizabeth Reinhardt says there's not enough money and letting fires burn is unpopular.
ELIZABETH REINHARDT: So many of the places where we have fire are near where people live. Or, say, it's early in the fire season and you have months of fire season ahead of you and you just don't feel like you can take the risk to have a big fire out there in the back country.
JOYCE: And the Forest Service, along with climate scientists, don't expect things to improve on their own. Over the past century, average global temperature has gone up more than one degree. Scientists say climate change is likely to keep pushing temperatures up. Climate scientist Anthony Westerling explains that in the West, heat dries up the land.
DR. ANTHONY WESTERLING: So you think of like a bathtub, all right? So the more you warm it up, the more the moisture is leaving the bathtub. It's coming out as steam off the top.
JOYCE: Trees and grass and bushes turn into dry tinder. Westerling works at the University of California in Merced, but he's been watching the Rocky Mountains a lot. He says spring is coming earlier, and it's hotter. Many forests there are near their heat and drought limit. And he says computer models show an even rockier long-term trend.
WESTERLING: By the time you get to mid-century in the Northern Rockies, temperatures in most years and drought in most years is far more extreme than the most extreme historical events.
JOYCE: And that will mean more firefighting, especially if people continue to build homes and subdivisions in fire-prone regions. Economist Ray Rasker says that's likely to continue if communities and developers who decide to build are not paying for their own fire protection.
RASKER: If they don't bear the full cost of that decision, the cost is borne by the federal taxpayer, by the rest of us.
JOYCE: And Rasker says this doesn't make ethical sense either.
RASKER: It's a tough thing to see people go in to have to risk their lives and to defend structures. That's - it's a tough thing to see as a nation.
JOYCE: Christopher Joyce, NPR News.
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