[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 <i>ten</i> 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]