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As you've probably noticed,
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in recent years, a lot of western forests have burned
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in large and destructive wildfires.
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If you're like me --
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this western landscape is actually why my family and I live here.
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And as a scientist and a father,
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I've become deeply concerned about what we're leaving behind
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for our kids, and now my five grandkids.
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In the US, an area that's larger than the state of Oregon has burned
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in just the last 10 years,
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and tens of thousands of homes have been destroyed.
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Acres burned and homes destroyed have steadily increased
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over the last three decades,
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and individual fires that are bigger than 100,000 acres --
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they're actually on the rise.
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These are what we call "megafires."
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Megafires are the result of the way we've managed this western landscape
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over the last 150 years
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in a steadily warming climate.
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Much of the destruction that we are currently seeing
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could actually have been avoided.
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I've spent my entire career studying these western landscapes,
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and the science is pretty clear:
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if we don't change a few of our fire-management habits,
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we're going to lose many more of our beloved forests.
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Some won't recover in our lifetime
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or my kids' lifetime.
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It's time we confront some tough truths about wildfires,
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and come to understand that we need to learn to better live with them
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and change how they come to our forests,
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our homes
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and our communities.
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So why is this happening?
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Well, that's what I want to talk to you about today.
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You see this forest?
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Isn't it beautiful?
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Well, the forests that we see today
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look nothing like the forests of 100 or 150 years ago.
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Thankfully, panoramic photos were taken in the 1930s
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from thousands of western mountaintop lookouts,
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and they show a fair approximation
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of the forest that we inherited.
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The best word to describe these forests of old is "patchy."
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The historical forest landscape was this constantly evolving patchwork
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of open and closed canopy forests of all ages,
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and there was so much evidence of fire.
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And most fires were pretty small by today's standards.
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And it's important to understand that this landscape was open,
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with meadows and open canopy forests,
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and it was the grasses of the meadows
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and in the grassy understories of the open forest
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that many of the wildfires were carried.
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There were other forces at work, too, shaping this historical patchwork:
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for example, topography, whether a place faces north or south
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or it's on a ridge top or in a valley bottom;
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elevation, how far up the mountain it is;
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and weather, whether a place gets a lot of snow and rain,
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sunlight and warmth.
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These things all worked together
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to shape the way the forest grew.
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And the way the forest grew shaped the way fire behaved
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on the landscape.
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There was crosstalk between the patterns and the processes.
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You can see the new dry forest.
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Trees were open grown and fairly far apart.
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Fires were frequent here, and when they occurred,
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they weren't that severe,
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while further up the mountain,
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in the moist and the cold forests,
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trees were more densely grown and fires were less frequent,
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but when they occurred, they were quite a bit more severe.
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These different forest types, the environments that they grew in
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and fire severity -- they all worked together
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to shape this historical patchwork.
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And there was so much power
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in this patchwork.
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It provided a natural mechanism
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to resist the spread of future fires across the landscape.
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Once a patch of forest burned,
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it helped to prevent the flow of fire across the landscape.
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A way to think about it is,
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the burned patches helped the rest of the forest
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to be forest.
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Let's add humans to the mix.
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For 10,000 years, Native Americans lived on this landscape,
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and they intentionally burned it -- a lot.
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They used fire to burn meadows and to thin certain forests
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so they could grow more food.
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They used fire to increase graze
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for the deer and the elk and the bison that they hunted.
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And most importantly, they figured out
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if they burned in the spring and the fall,
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they could avoid the out-of-control fires of summer.
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European settlement -- it occurred much later, in the mid-1800s,
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and by the 1880s, livestock grazing was in high gear.
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I mean, if you think about it, the cattle and the sheep ate the grasses
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which had been the conveyer belt for the historical fires,
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and this prevented once-frequent fires from thinning out trees
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and burning up dead wood.
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Later came roads and railroads, and they acted as potent firebreaks,
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interrupting further the flow of fire across this landscape.
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And then something happened which caused a sudden pivot
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in our society.
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In 1910, we had a huge wildfire.
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It was the size of the state of Connecticut.
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We called it "the Big Burn."
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It stretched from eastern Washington to western Montana,
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and it burned, in a few days, three million acres,
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devoured several towns, and it killed 87 people.
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Most of them were firefighters.
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Because of the Big Burn, wildfire became public enemy number one,
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and this would shape the way that we would think about wildfire
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in our society
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for the next hundred years.
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Thereafter, the Forest Service, just five years young at the time,
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was tasked with the responsibility of putting out all wildfires
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on 193 million acres of public lands,
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and they took this responsibility
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very seriously.
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They developed this unequaled ability to put fires out,
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and they put out 95 to 98 percent
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of all fires every single year in the US.
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And from this point on, it was now fire suppression
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and not wildfires
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that would become a prime shaper of our forests.
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After World War II, timber harvesting got going in the west,
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and the logging removed the large and the old trees.
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These were survivors of centuries of wildfires.
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And the forest filled in.
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Thin-barked, fire-sensitive small trees filled in the gaps,
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and our forests became dense, with trees so layered and close together
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that they were touching each other.
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So fires were unintentionally blocked by roads and railroads,
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the cattle and sheep ate the grass,
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then along comes fire suppression and logging, removing the big trees,
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and you know what happened?
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All these factors worked together
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to allow the forest to fill in,
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creating what I call the current epidemic of trees.
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(Laughter)
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Go figure.
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(Laughter)
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More trees than the landscape can support.
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So when you compare what forests looked like 100 years ago and today,
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the change is actually remarkable.
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Notice how the patchwork has filled in.
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Dry south slopes --
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they're now covered with trees.
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A patchwork that was once sculptured by mostly small
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and sort of medium-sized fires
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has filled in.
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Do you see the blanket of trees?
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After just 150 years,
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we have a dense carpet of forest.
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But there's more.
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Because trees are growing so close together,
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and because tree species, tree sizes and ages
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are so similar across large areas,
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fires not only move easily from acre to acre,
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but now, so do diseases and insect outbreaks,
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which are killing or reducing the vitality
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of really large sections of forest now.
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And after a century without fire,
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dead branches and downed trees on the forest floor,
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they're at powder-keg levels.
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What's more, our summers are getting hotter
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and they're getting drier
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and they're getting windier.
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And the fire season is now 40 to 80 days longer each year.
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Because of this, climatologists are predicting
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that the area burned since 2000
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will double or triple
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in the next three decades.
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And we're building houses in the middle of this.
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Two recently published studies tell us
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that more than 60 percent of all new housing starts are being built
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in this flammable and dangerous mess.
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So when we do get a fire,
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large areas can literally go up in smoke.
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How do you feel now
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about the forest image
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that I first showed you?
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It scares the heck out of me.
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So what do we do?
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We need to restore the power of the patchwork.
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We need to put the right kind of fire
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back into the system again.
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It's how we can resize the severity of many of our future fires.
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And the silver lining is that we have tools
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and we have know-how to do this.
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Let's look at some of the tools.
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We can use prescribed burning to intentionally thin out trees
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and burn up dead fuels.
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We do this to systematically reduce them and keep them reduced.
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And what is that going to do?
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It's going to create already-burned patches on the landscape
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that will resist the flow of future fires.
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We can combine mechanical thinning with some of these treatments
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where it's appropriate to do so,
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and capture some commercial value
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and perhaps underwrite some of these treatments,
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especially around urban areas.
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And the best news of all is that prescribed burning produces
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so much less smoke than wildfires do.
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It's not even close.
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But there's a hitch:
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prescribed burning smoke is currently regulated under air quality rules
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as an avoidable nuisance.
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But wildfire smoke?
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It simply gets a pass.
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Makes sense, doesn't it? (Laughs)
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So you know what happens?
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We do far too little prescribed burning,
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and we continually eat smoke in the summers
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from megafires.
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We all need to work together to get this changed.
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And finally, there's managed wildfires.
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Instead of putting all the fires out,
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we need to put some of them back to work
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thinning forests and reducing dead fuels.
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We can herd them around the landscape
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when it's appropriate to do so
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to help restore the power of the patchwork.
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And as you've probably figured out by now,
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this is actually a social problem.
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It's got ecological and climate explanations,
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but it's a social problem, and it will take us humans to solve it.
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Public support for these tools is poor.
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Prescribed burning and managed wildfires are not well-supported.
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We actually all simply want fires to magically go away
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and take that pesky smoke with them, don't we?
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But there is no future without lots of fire and lots of smoke.
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That option is actually not on the table.
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Until we, the owners of public lands, make it our high priority
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to do something about the current situation,
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we're going to experience continued losses to megafires.
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So it's up to us.
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We can spread this message to our lawmakers,
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folks who can help us manage our fires
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and our forests.
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If we're unsuccessful,
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where will you go to play
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when your favorite places are burned black?
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Where will you go
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to breathe deep
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and slow?
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Thank you.
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(Applause)