How Fighting Wildfires Works

How Fighting Wildfires Works
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    It's 4 am on a mid-August morning in the northern California wilderness.
    During a brief overnight storm, lightning strikes the top of a hill, ignites some dry
    underbrush, and starts a wildfire.
    It isn't until 6am as the sun rises that someone notices the fire—a hiker camping
    an overlooking hill.
    As soon as the hiker's 911 call is received by the emergency dispatch center they contact
    Cal Fire—the agency responsible for wildfire protection and management in California.
    By 6:30, they call the Redding, California based smokejumpers.
    They are one of most elite firefighting squads in the United States.
    There are only 400 smokejumpers in the US and 40 of those are based here in Redding,
    They're essentially the rapid response team for wildfires.
    Within 15 minutes of receiving the call, these smokejumpers are in their plane and taking
    It takes just 20 minutes to fly the 50 miles to the fire site where they find a suitable
    tree-free landing spot, jump, deploy their parachutes, and land.
    The plane then circles back to parachute down boxes of equipment.
    Smokejumpers carry with them enough supplies to last 72 hours completely self supported—food,
    water, shelter, safety equipment, and firefighting tools.
    They follow the ridge line and make their way to the fire.
    Now, this is a small team and they need to decide how to prioritize what they do.
    With the fire already having grown to 15 acres the team knows they're unlikely to stop
    it on their own, backups are already on the way, so their priority is to slow it down
    as much as possible.
    There are four major factors that affect how fast a fire moves: how much fuel there is,
    how wet the fuel is, the wind direction, and the slope.
    The two factors that the team can immediately gauge that affect where the fire will move
    the fastest are the wind direction and slope.
    In this case the wind is coming from the north and they know that to the south-west is an
    upward slope.
    Fire moves faster uphill than it does downhill since fire burns upwards so these smokejumpers
    know that this is likely the fire's fastest moving front.
    While trees do burn, the primary source of fuel that a wildfire uses to move is the dry
    brush and dead wood on the forest floor so the biggest technique used to stop forest
    fires is to create what's called a fire line.
    These are essentially a gap where they remove all fuel—plants both dead and alive—so
    that there's nothing for the fire to continue burning.
    The smokejumpers use a mix of chainsaws and other hand tools to do this work but sometimes
    fire lines are pre-built.
    In this case there's a road at the top of the uphill section which will help slow or
    stop the fire so they can direct their efforts elsewhere.
    They use the road as their anchor point—a cleared section that the fire likely won't
    cross where they start building their fire line so the fire can't outflank them.
    Throughout this construction process the smokejumpers need to be sure that they can escape in case
    the winds shift or the fire picks up speed.
    Wildfires can move exceptionally fast—up to 7 miles per hour in forests which is faster
    than humans are often able to make their way through dense trees.
    In grasslands fires can move up to 14 miles per hour so firefighters have to be extra
    For this reason firefighters rarely put themselves directly in front of the fire's moving front—they'll
    either be far ahead or to the side.
    In the case of this fire as they're building this first fire line they're close to a
    road which acts as an easy exit point but, just in case, all smokejumpers carry fire
    These compact, lightweight shelters won't survive direct flames for too long, but they
    do greatly increase a firefighter's chance of survival in case they can't escape the
    path of the fire.
    After a little over an hour of work the smokejumpers complete a continuous fire line from the road
    to a stream.
    Streams, while less secure than roads, also help stop or slow down a fire by acting as
    a fire line.
    To the south-east of the fire there's also a small road that connects to another stream
    meaning there are at least rudimentary fire lines on three sides of the fire.
    It's at this time when backups arrive by road.
    The added manpower allows for much faster action.
    The immediate focus goes to strengthening the southeastern fire line—currently just
    a stream.
    At closest the fire's less than 100 feet from the stream and the stream is itself in
    a valley so it's too risky to work directly behind the stream, there's just no good
    escape route, so the new arrivals get to work on a redundant fire line 100 feet behind the
    By 10 am the fire has further grown and the team knows that the worst is still to come.
    Fires spread most rapidly between 10am and sunset due to the daytime heat and wind.
    By 11am the fire has reached the road and part of the fire line which means that some
    of those that were building the fire-line are re-allocated to make sure that the fire-line
    holds—extinguishing any flames that may jump the road.
    By noon the fire lines are holding and, while the fire's size is growing, it's at a
    manageable pace so there's reasonable hope that it can be suppressed before expanding
    to an uncontrollable size.
    At 1pm, though, conditions change.
    The wind starts blowing harder towards the south-west and, as trees burn on the north
    side of the road, the wind pushes embers over the road which ignite underbrush on the other
    side and now the entire focus of the firefighting efforts change.
    You see, the point of fighting wildfires is not actually to put them out, it's to control
    While the number of wildfires has increased due to humans they're actually a very natural
    What's making wildfires worse is humans stopping them.
    Many forests survive wildfire through trees having heat-resistant bark and other evolutionary
    These fire resistant forests relied on having wildfires at a consistent interval every few
    decades to clear out the forest floor of dead plants and to kill invasive species.
    Nowadays, though, as humans suppress fires a forest might only see a wildfire every 50
    years instead of 25, for example, meaning that there's twice as much fuel and so the
    fire burns faster, larger, and more intensely.
    It was only until recent years that the research revealing this was widely accepted so the
    goals of firefighting shifted from stopping wildfires completely to controlling them.
    In some places, being a firefighter actually means starting fires.
    Fire management agencies will conduct controlled burns in order to reduce the risk of an uncontrollable
    fire and to increase the health of a forest.
    While forests can survive wildfires, humans cannot so most agencies will let fires burn
    in a controlled fashion up until the moment they risk damaging property or threatening
    human life.
    This fire that jumped the road just did exactly that.
    At the bottom of this slope is a town and the fire is now headed in that direction with
    no preexisting features to stop it.
    That means that all measures must be taken to aggressively stop the fire's expansion
    to the west.
    That means it's time to bring out the big guns—it's time to attack the fire from
    Planes and helicopters are some of the most effective tools used to fight wildfires.
    They can quickly and accurately drop huge amounts of water or fire retardant.
    The decision to use aerial firefighting does not come lightly as it's both hugely expensive
    and using an aircraft on one fire means it can't be used on another.
    Their use needs to be prioritized for the most dangerous fires.
    There's also a decision to be made on what the aircraft is going to drop—water or flame
    Water is cheap and, with some aircraft designs, can be reloaded near the fire without landing
    at an airport.
    Water is only effective at extinguishing flames, though.
    Flame retardant, on the other hand, can be used to stop flames from starting.
    It can essentially create a fire line ahead of the fire's spread as it will stop a line
    of forest from burning.
    The main issues, though, are that flame retardant can only be loaded at an airport and it's
    very expensive.
    A gallon of Phos-Chek, the most commonly used brand of flame retardant, costs $3.
    That's about the same as a gallon of milk at the grocery store but these aircraft use
    thousands of gallons of it for each drop.
    The world's largest firefighting aircraft, the 747 supertanker, for example, carries
    19,600 gallons of flame retardant meaning that what it uses in one drop costs nearly
    Of course there's a reason agencies hire this plane, it creates a 3 mile long fire
    line almost instantly, but it comes at a steep price.
    For this fire, using such an expensive tool would be overkill.
    In this case, they'll use a helicopter with a bucket attached.
    The bucket is filled with water from a nearby lake then the helicopter flies over to the
    fire and drops it.
    With only 5 miles to the lake the helicopter is able to make a drop about every 5-10 minutes
    and, while it works on stopping the spread on one side hand crews work on building a
    fire line on the other.
    The area that the helicopter extinguishes essentially acts as its own fire line as fire
    can't burn what's already burned.
    This work continues for the next few hours—its vital to not let anything to the south-west
    of the road burn out of control.
    By 4pm the outbreak is managed and attention can be directed back to the largest section
    of the fire.
    As the afternoon wears on some crews get back to lengthening the eastern fire line, others
    begin constructing a western fire line, and the helicopter works on slowing the advancement
    to the north.
    By the time the sun begins to set around 8, all sides of the fire have at least some element
    of control so that during the night and in the coming days the fire can continue to burn
    in a controlled fashion until there's nothing left to burn.
    This mission was a success but the reality is that this is not a real fire.
    Real fires rarely end this well.
    Real fires don't act so predictably because real fires can't be predicted.
    Real fires are a menace that can grow to the size of small countries and can burn for months.
    During summer and fall, there are often more than 100 large forest fires burning around
    the US at any given time and thousands more around the world.
    No firefighting effort is exactly like another but these are the primary techniques used
    by those who work everyday to protect life and property from one of nature's most dangerous
    Whether you're fighting forest fires or running a business the tools you use are crucially
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