[TED intro plays]
Have you ever wondered what it's like to be a tree?
Nobody. [audience laughs]
Ah, there's somebody.
See, I thought it was just me,
but for me, I think--
Oh, there's more of you out there.
But I think for me, it's actually a side effect of my job.
I work on mountain pine beetle,
and this insect has the dubious honor of having developed,
over just the last few years, what is very likely
to be the largest insect outbreak ever recorded by humans
on the planet.
And this tiny little insect,
the size and appearance of a mouse turd,
has managed to kill millions and, in fact, billions of trees
across vast landscapes.
Now, when I'm out working in the forest,
I actually do think about what it means to be a tree.
Now, obviously, they're quite different from us.
They're made of wood; we're made of flesh and blood,
but I see another big difference.
Trees can't walk.
Trees can't run.
And trees can't hide.
And that means
that when a enemy like mountain pine beetle shows up,
they have no choice
but to stand their ground.
Now, most of us, when we think about trees,
we think about these nice, gentle, passive,
benign organisms,
but nothing could be further from the truth.
Trees
are dangerous.
[laughter]
I see some skeptics out there,
but really, put yourself in the place of a tree.
What would you do?
Would you just stand there?
Would you fight back?
You'd fight back.
And that's exactly what trees do.
Trees are armed with an amazing array
of physical and chemical weapons.
They fight back, and they fight back really hard.
So if you're a mountain pine beetle,
trees pose a significant challenge.
In fact, it takes hundreds
and sometimes even thousands of beetles
to kill a single tree.
Now,
if not enough beetles show up,
that's a dangerous situation,
because that means the tree wins and the beetles die.
So it's actually very risky
to be a mountain pine beetle,
and even when they're successful,
it hardly seems worth the effort.
Trees are the epitome of junk food.
Woody tissues have almost no nutrients,
and beetles can't live on wood much easier than we can.
So how do they do it?
Well, guess what, they do it the same way we do.
When they've been eating a lot-- well,
when we've been eating a lot of junk food,
we pile on those nutritional supplements,
and that's exactly what they do,
only in a very different way as you might suspect.
The beetles actually partner with a couple of fungi
that provide to them everything that wood cannot:
vitamins, nitrogen to make proteins,
sterols to make hormones, and so forth.
Pretty cool.
By partnering with fungi,
beetles can use trees to raise their kids,
but being able to use a tree for food
is just the first step in developing an outbreak.
What is it that actually allows these beetles
to develop such huge numbers
that they can kill you, if you're a tree,
and your family and your friends
and, in fact, the entire forest?
Well, you'll hear from a lot of people
that the reason we have this big outbreak
is because we have unhealthy forests,
or because we have too many pines,
or because we have too many big pines,
or too many lodgepole pines,
that if we had only managed our forest,
none of this would have happened.
But that's not exactly true.
As you might suspect,
there's a little bit more to that story.
So let me explain how this big outbreak developed
and why this one is so unusual
compared to those that we've seen in the past.
First, you need to know a little bit about the insect.
One thing, outbreaks aren't new.
Mountain pine beetle is actually native to western North America,
and it's been developing outbreaks there for millennia,
and these outbreaks are actually natural disturbances.
They help maintain and restore the forest.
But, clearly,
beetles are not in outbreaks all the time.
They only develop outbreaks every few decades or centuries,
and only when you have two things:
you need to have lots of pines on the landscape
that are big enough for the beetles to use,
which is a condition we always have,
and a trigger.
So let me explain this trigger.
What you see here is what a mountain pine beetle population
might look like for a couple of hundred years,
and what you can see is that the beetle
is present in very low numbers most of the time.
And so at this point, if you're a tree,
you should feel very safe,
because the beetles are actually
at the mercy of their own low numbers.
There are so few of them out there,
they can hardly ever kill a tree,
and those few trees they actually kill have disease or they're damaged
and can't fight back.
But of course, somewhere along the way,
we get a trigger,
and for mountain pine beetle, the trigger
is a change in climate
to warmer and drier conditions.
And at this point, if you're a tree,
you should start to worry
because warmer temperatures
allow greater productivity of beetle young
and greater survival of their young over the winter,
and that means more beetles,
and drought stresses trees,
and that lowers their defenses,
and that lowers the numbers of beetles it takes to kill them.
And very importantly, drought stresses trees across regions,
so that's really big areas.
So if you're a tree,
this is a really bad combo.
It means you've got a lot of beetles out there,
but it doesn't take very many to kill a tree,
and there's lots and lots and lots of trees
that are easy to kill.
This situation allows the beetles to rapidly build in population
until they reach a threshold
over which there are so many beetles
that they can even kill healthy, defensive trees.
At this point,
tree defenses are inconsequential.
They no longer matter.
And, in fact, the beetles switch
to attacking healthy trees
because they're better food for their young,
and better food for the young means...
more beetles.
At this point, the outbreak is self-perpetuating,
and there's virtually nothing you can do to stop it.
Now, once an outbreak initiates,
there's a couple of potential end points.
One, it can go to completion,
and that means that they-- the beetles,
kill most of the suitable trees on the landscape,
and then their populations crash
because they're out of food.
But in the past, this seldom ever happened.
You had the initiation of an outbreak
when you had an abnormally warm, dry period,
but when things went back to normal,
got cooler and wetter,
then tree defenses came up;
beetle productivity went down,
and the beetles pooped out.
But the problem now is, of course,
that we're not expecting to go back
to cooler, wetter conditions.
The predictions are we're going to get warmer
and in many places drier,
and that means that going to completion
might be the new norm.
And if that's the case, we need to be really concerned,
because that means really big changes
in our forest ecosystems,
and of course, then, big changes in all those services
and functions that they provide.
Now, the current outbreak
is actually, or maybe, a harbinger of things to come.
This outbreak is significantly different
than any we've seen in the past.
For one, it's *ten* times bigger,
ten times.
Now, that's pretty remarkable in and of itself.
But there's more.
The beetle is actually on the move.
Because of warming, the beetle has moved
several hundred kilometers further north in Canada,
and it's now all the way to the Yukon.
It has jumped the Northern Rockies
and has spread across Alberta
and is now even invading Saskatchewan.
In this location in Canada,
the beetle is in a new place;
it's in a new species of tree,
and that makes it an exotic.
And we know that exotics
are seldom very good
for our native ecosystems.
The beetle is expected to continue to move across the continent,
through the boreal forest
and into our eastern pine forests.
Because of warming, the beetle has also moved up in elevation
where it's wiping out white bark pine.
This is a tree that used to be protected from the beetle by cold,
but now the devastation is so extensive and severe,
this critically important tree
is now being recommended for listing
as an endangered species.
And all of this has been due
to a warming climate.
Now, I mentioned that this particular outbreak
is far outside the historic norm,
and as such, in many locations,
the beetle is no longer restorative for the forest,
but damaging.
Effects on water, vegetation,
wildlife, local communities,
and economies have been massive.
And human responses,
for better or for worse, to the outbreak
have added an additional level of impact.
At this point,
if you're a tree,
you should not only be worried;
you should be shaking in your roots.
[person laughs] Sorry, bad one.
[laughter]
Couldn't help it.
But, also, if you think about this-- this outbreak,
it's really tempting to think of it as a local issue:
It's just western North America,
but actually, the implications are global.
Trees are incredibly important sinks for carbon,
but when vast areas die,
they become sources.
In the worst year of the outbreak,
carbon emissions from beetle kill in British Columbia alone
are predicted to have equaled the carbon releases
from fires across all of Canada
for the preceding forty years.
Those kinds of carbon releases
obviously can feed back to affect humans
and ecosystems all around the world.
Now something else to actually think about as well
with mountain pine beetle is to realize
that this situation is not unique.
Climate-driven tree die-offs are happening right now
all over the world.
Take, for example, the giant Euphorbia tree
that I work on in Africa.
It's being mass attacked by ambrosia beetles.
These are tiny, little beetles
related to the mountain pine beetle,
but they're typically not a problem.
But because of increasing temperature,
decreasing precipitation,
these trees are stressed,
and the beetles are responding.
This iconic poison arrow tree of Africa
is very likely to disappear
from many portions of its range
just over the next decade.
the massive piñon bark beetle ips in the southwestern US
has been so severe and extensive
that many of these forests are not expected to recover.
Over eighty tree species around the world
are known to be in trouble due to climate change,
and likely there's a whole lot more
that we haven't yet recognized.
So, what do we do?
What do you do?
What do I do?
What do the trees do?
Well, unfortunately, we can't just go out there somewhere
and turn down a thermostat.
We can't lay out
thousands and thousands of miles of irrigation,
even if we could come up with the water.
And logging won't do much if it's driven by climate.
So we need to finally go to the root of the problem
and do something about our emissions of greenhouse gasses,
and we need to do it soon.
We also need to develop new tools and approaches to our forests.
We need to move away from thinking
that logging will fix everything,
and we need to start working with our knowledge
of genetics and adaptation.
And very importantly, we need to remember
that trees can't walk;
trees can't run,
and trees can't hide,
and with increasing stress,
trees are going to have fewer and fewer defenses at their disposal,
and somehow it's going to be up to us to get them through.
I hope I've opened some eyes and minds tonight about the threat
that a warming climate poses to our forests,
but I also hope I've helped people recognize
that these threats are not just through effects on the big things,
like ice shelves
and sea level rise
and extreme weather,
but through their effects on the little things,
like a tiny little insect
the size and appearance
of a mouse turd.
Thank you.
[applause]