WEBVTT
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♪ (music) ♪
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It was just a fireball,
and it traveled so fast.
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I just saw flames
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all up on the hill behind my house.
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It was Armageddon, I'll tell you.
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The fire coming in
and burning all around us.
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(narrator) Alaska, Arizona,
California, Montana, Oregon,
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Australia, Brazil,
Canada, Greece, Russia--
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these are just some of the places
where in recent years
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wildfires have raged out of control.
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NASA satellites detect
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more than a million large fires
worldwide every year.
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(Doug) The Western United States,
for example, has seen larger fires
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in each of the last several years
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and more intense burning,
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and many times those fires spread faster,
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making them more difficult to put out
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and more dangerous for the communities
who live in that vicinity.
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(narrator) In many cases,
the blazes are set by human activity,
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but sometimes policy fuels the flames too.
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Consider California.
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The state's forests are overgrown
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in part because of past federal policies
of putting out wildfires
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rather than letting them burn.
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Some of these policies were enacted
in response to a devastating fire in 1910,
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in which millions of acres burned
and more than 80 people died.
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Years passed, and suppression
became the go-to strategy
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for dealing with fire.
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(reporter) It only takes a minute
to wipe out a century.
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(narrator) Initiatives like Smokey Bear
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urged Americans
to help prevent forest fires.
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(Smokey Bear) Only you
can prevent forest fires.
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(narrator) In 1974, Congress passed
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the Federal Fire Prevention
and Control Act
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in an effort to save lives,
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and that plan worked.
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Around that time, according to the Act,
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fires of all types killed
more than 12,000 people each year.
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Today, according to
the U.S. Fire Administration,
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the death toll is lower,
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but...
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(Doug) Part of the reason
we see increasing fuels
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and increasing extreme fire behavior
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is that we have a legacy
of putting fires out
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and allowing fuels to grow,
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permitting fires when they do start
to get out of control,
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(narrator) Overgrown forests
have an abundance
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of small and medium trees,
known as ladder fuels,
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which can make fires more dangerous.
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Ladder fuels would allow a surface fire
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burning often slowly along the ground
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to transition into the canopy
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where it can spread more rapidly.
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And when those trees are burning,
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the embers that are blown by the wind
can ignite the neighboring trees
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that can also be spread further downwind.
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(narrator) That's part of the story
of California's 2018 fire season.
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The deadly campfire
was fed by dry weather,
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fast winds, and ladder fuels.
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According to recent research,
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20 million acres of forest land
or nearly 20% of California
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would benefit from what's known
as fuel treatments.
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Land managers can limit the fuels
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that could create large,
fast-moving fires
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in several ways,
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including getting out vegetation--
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think logging or clearing brush--
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prescribed burns
where small fires are set deliberately,
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or letting natural wildfires
in unpopulated areas
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run their course under the watch
of local firefighters.
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But clearing out brush
can be expensive and labor-intensive.
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First, many of these trees
are small in diameter,
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so they don't have
commercial value as timber
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and there's little financial incentive
to remove them,
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and federal policies
have historically favored
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putting out fires as soon as they start,
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to keep people safe.
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Maintaining that balance
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of different ecosystem types
and different fire frequencies
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is more difficult when we move into areas
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with more dense human populations.
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And so the wild land urban interface
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is really where these two challenges meet,
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where people are living in communities
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against landscapes
that historically have had fire activity.
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Those are landscapes
that are very difficult to protect
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when fires do start.
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(narrator) One of the factors
affecting California's wildfire season
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is new housing construction
in fire prone areas.
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Climate change is adding
to the problem too.
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(Doug) Where fuels are abundant today
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and where climate change is leading
to warmer and drier conditions,
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we are already seeing
more extreme fire behavior.
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(narrator) According
to recent federal data,
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the last decade was the warmest on record.
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During the summer of 2020,
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fires burned in the Arctic,
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as parts of Siberia broke the record
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for the highest temperature ever recorded
above the Arctic Circle.
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They're almost always too cold
and too wet to burn.
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So, as those landscapes,
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which are warming three times faster
than the rest of the planet,
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continue to warm and dry,
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we certainly expect to see more fires
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in those remote landscapes
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directly in response to climate change.
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(narrator) In August of 2020, wildfires,
most of them sparked by lightning,
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raged out of control across California.
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Earlier in the year, state officials
had warned of high fire danger
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caused by a dry winter and warm spring.
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It's a pattern scientists
generally attribute to climate change.
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In May, the mountain snowpack
in California, Sierra Nevada
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was just 13% of normal.
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And it's not just 2020.
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Half of California's
20 most destructive wildfires
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have happened since 2015.
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Across the forests of Southeast Australia,
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NASA mapped more fires
between 2019 and 2020
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than they had in the last 16 years.
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The fires were fueled
by extreme heat and drought.
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Hotter, drier weather
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sucks moisture out of the trees,
grasses, and other fuels,
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making them more flammable.
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And this is making fire management
all the more complicated.
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So as conditions that allow
wildfires to spread
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are lasting longer across
the United States and elsewhere,
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there's a shorter and shorter window
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where active management
could happen under conditions
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that wouldn't risk fires
escaping and spreading
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into lands as a wildfire.
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(narrator) That means
fighting fire with fire
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might not be an option
for certain regions anymore.
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So to help with wildfires,
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researchers are working on algorithms
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to improve forecasting.
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(Doug) If we can anticipate the timescales
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and the locations
where fires are most likely,
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we have the best chance of trying
to mobilize and prepare resources
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to anticipate fires
and make a more timely decision
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about which fires to put out
and which to let burn.
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♪ (music) ♪