SCOTT SIMON, host:
This is WEEKEND EDITION from NPR News. I'm Scott Simon.
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Firefighters are busy across the western United States. This weekend, more than two-dozen large wildfires are burning in Idaho and Montana. These are local concerns, but scientists say they're also increasingly part of a global pattern, a result of shifts in the planet's climate.
As part of our Climate Connection series together with National Geographic, NPR's Jeff Brady traveled to Idaho this week. His report begins on the outskirts of Boise, a hundred miles from one of the biggest fires.
JEFF BRADY: The entire valley is just filled with smoke. It smells sort of like one big campfire here. And that smoke is just going to get more intense as we head up toward the fires.
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BRADY: Two hours later, we're at the Sheep Trail Fire. It's burned 7,000 acres over the last couple of weeks, but today, the fire is just creeping along because an air inversion has trapped cooler air near the ground. My guide is forester Carl Pence(ph). We stopped about 20 feet from the fire.
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BRADY: It's difficult to walk through here. I mean, there's - every couple of steps, there's a tree in your way.
Mr. CARL PENCE (Forester): Yes, that's a fact. You know, we have had about a hundred years of fire suppression in the forest service career. We suppress fire in these stands illogical in this particular area, and it has created a continuity of fuels.
BRADY: A fuel ladder from the ground to the treetops, dried out twigs, waste hide brush and dead trees leaning every which way. Pence says this is a forest just waiting to burn. And there are overgrown forests just like it all over the west. Now, on top of that, says Tom Swetnam of the University of Arizona, there's climate change.
Professor THOMAS SWETNAM (Dendrochronology, University of Arizona): We're seeing these large, large fires and they're probably related in part to these patterns of warming occurring around the globe.
BRADY: Many have predicted this, but Swetnam and his colleagues published a research paper last summer that says it's already underway in the Western U.S.
Ron Neilson with the U.S. Forest Service says it's happening all over the world, too. He uses global computer models to predict how climate change will affect plants overtime. He says the predictions look contradictory at first.
Mr. RON NEILSON (Bioclimatologist, United States Department of Agriculture Forest Service): With a little bit of warming, the planet should actually green up a bit, and that's because you also get increased rainfall.
BRADY: But, Neilson says, that won't last. His models show forests being tricked into growing beyond what the available water can support, and then they'll start to turn brown. He's not sure how this will play out in different parts of the world, but he's especially concerned about the southeastern United States because the climate and the terrain don't vary much.
Mr. NEILSON: One point is ready to go up. A whole huge area is ready to go up.
BRADY: In May, the dried out Okefenokee Swamp caught fire, merged with another blaze and eventually scorched an area the size of Rhode Island.
Mr. NEILSON: Now transport yourself up into the boreal forest.
BRADY: That's about a forest that spreads mostly across Canada and Russia. Much of it is permafrost that Neilson says is melting and exposing deep layers of peat soil that has locked away carbon for thousands of years. When those forests catch fire, Neilson says, huge amounts of carbon will be released, speeding up climate change even more.
In Russia, a Slavic version of "Smokey Bear" is now appearing on television sets.
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Unidentified Man: (Russian spoken)
BRADY: Now let's head back south toward the equator. This is a region Ayn Shlisky is worried about. She heads the Nature Conservancy's Global Fire Initiative. Last spring, she released a first of its kind planet-wide report on the state of wildfires.
Shlisky says dense tropical forests haven't seen much fire, but they're likely to get drier and some will burn.
Ms. AYN SHLISKY (Director, Nature Conservancy's Global Fire Initiative): And so we're likely to lose many, many species. They can't survive more frequent fire regimes as well as all of the animal species that are dependent on those tropical systems.
BRADY: Back here in the U.S., the Forest Service is spending more than 40 percent of its budget on fires, but not everyone agrees with that policy.
Mr. ANDY STAHL (Executive Director, Forest Service Employees for Environmental Ethics): If the Forest Service continues as it's going spending on fire, this will no longer be the Forest Service, it will be the fire service.
BRADY: Andy Stahl heads a group called Forest Service Employees for Environmental Ethics. He believes the agency should stop its war on fire and teach people to live with it instead. He says fire is natural and necessary. But the timber industry believes forest should be managed to prevent fires, and also store carbon.
Chris West with the American Forest Resource Council says the way to do that is to remove carbon-releasing dead trees and plant carbon-hungry new ones.
Mr. CHRIS WEST (Vice President, American Forest Resource Council): Hence, we need to go in there and remove those trees, capture that carbon that's in those trees - either putting it into lumber and wood products or producing bio-mass out of it - and will turn the forest to a condition that they can sustain themselves on.
BRADY: But this forest in Idaho is still burning, and the winds are picking up. Carl Pence says it's almost time to leave.
Mr. PENS: I was just noticing that the inversion started to lessen just a little bit, and you can see that the flames are starting to climb up (unintelligible) the trees a little bit. That's a serious sign that we better be alert and consider safety here. So we want to be heads up here and stay safe.
BRADY: We head back to Boise through miles and miles of overgrown forests ready for large fires that are more likely to come with a warming climate.
Jeff Brady, NPR News, Boise, Idaho.