[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]