I recently moved from a place 
that had a backyard that looks like this,

to one that looked like this.

There are a lot of great
things about cities,

but access to nature
isn't always one of them.

Many days I felt like
the closest thing I got to nature

was looking at grainy
cat videos on YouTube.

(Laughter)

I'm sure some of you can relate.

Sometimes you don't realize how important
something is to you until you lose it.

I wasn't like Woody Allen who once said:

"I love nature, I just
don't want any of it on me."

(Laughter)

I wanted it on me, and I missed it.

When I moved for my husband's job
from Boulder, Colorado, to Washington DC,

I wasn't too happy about it.

But I was still surprised by how swiftly
my sense of well-being plummeted.

I got depressed,
I was anxious, I felt irritable.

My brain felt sluggish and dull.

I had to get used to new sounds, 
like overhead aircraft all the time,

helicopters and those ubiquitous
leaf blowers that I hear all the time.

But fortunately, shortly after I moved,

I was given a dream assignment
by Outside Magazine

to go visit the national forests of Japan

to write about an obscure practice
called "shinrin yoku," or forest bathing.

This essentially involves
just being on a trail:

walking, sometimes sitting, 
sometimes just lying on a boulder

and letting nature pour
into all of your senses.

So perhaps imagine with me
for a minute what this might be like.

You're sitting there and you're hearing
the birds and the crickets.

You're smelling the rich loamy earth
and maybe the scent of fresh pine trees.

You can feel the breeze on your cheek
and the moss under your feet.

How do you think this makes you feel?

Well, scientists in Japan wanted
to answer precisely that question.

And so in a series of experiments
they sent 84 stressed-out college students

to go hang out for 30 minutes
in these forests

and then also to go hang out
on a city street.

And here's what they found -

this is me doing one of the experiments:

A 16% drop in the stress hormone cortisol.

A 2% drop in blood pressure.

A 4% drop in heart rate.

This is among the forest visitors.

None of that happened
in the people who went to the city.

And the people who went to the forest also
reported less anxiety and better moods,

whereas the opposite happened
in the people who went to the city.

So, nature has superpowers for us.

And there's even a dose effect:

it looks like the more time you spend
in nature, better things can happen.

So in Japan they sent some
of these students,

or some other people, some volunteers,

to go spend three days at a forest lodge.

And they found a 40% increase

in an immune cell 
called natural killer cells

It's critical to the immune system.

When they went to vacation
in the city that didn't happen.

So it's not just a vacation effect,
there's something about nature.

I became so intrigued by this story
and by this science

that I took another assignment
from National Geographic.

And this one sent me to a handful
of other countries around the world

studying this topic
to improve the health of citizens,

sometimes even going as far as
to recommend nature as medicine.

So in Japan, as we just saw, there are
these forests therapy trails.

They have 48 of them.

Korea will have 37
healing forests by next year.

These are entire forests.

And to go along with that,
they're training 500 healing rangers

to lead programs for everyone,
from digital addicts to school bullies.

The school bullies, by the way,

take a train called "the happy train"
from the city to the forest.

(Laughter)

Also programs for firefighters with PTSD,

and even prenatal women
and cancer patients,

I mean, it just goes on and on
what they're doing there.

I also went to Finland.

And Finland has gone so far as
to recommend, it's a very precise country,

they recommended a specific dosage
of nature to ward off depression.

And what they recommend, take note:

five hours a month of being in nature
or a little over an hour a week.

Now, Finland is really fortunate because
it's a country covered with forests

and coastlines and parks.

But many parts of the world
are not so lucky.

Already, over half of us
in the world live in cities.

And by 2050 that proportion will be 70%.

So making cities green and livable

will be one of the greatest
challenges of our century.

How can cities and civic institutions
make spaces of awe and restoration?

The city of Wellington, New Zealand, 
has made a space of awe

by designating and signposting
a snorkel trail very close to downtown,

where you can just jump
in the water, swim around,

and she things like octopus,
and butterfish and seahorses.

How cool is that?

Seattle offers low-tide walks

where children love to see
sunstars and moon snails.

In Singapore there are parks 
interspersed with public housing projects

so that people from all over the city
have access to nature.

And the city also encourages
architects and developers

to incorporate butterfly-loving
vertical gardens

into corporate and residential towers.

When my cab driver
dropped me off at this hotel,

he said how handy it was
I was staying here,

because I could just wake up
in the morning and start grazing.

(Laughter)

The University of California at Berkeley
has created a space of awe

by protecting one of the tallest
hardwood groves in North America.

And this is great because the students
can go here to recover from stress

and psychologists at the University
can study it happening.

So one way to do this

is they sent students go look up
at this grove of trees for one minute

and they also sent another group

to look up at a building
on campus for one minute.

And in a clever bit of trickery,

a research assistant dropped a box of pens
in front of each subject.

So guess who helped her
and picked up more pens:

people in the forest
or the people looking at the building?

If you guessed the forest,
you are correct.

And it only took one minute
of them feeling awe

to behave in a more generous way.

So it looks like time outside in nature
can also make us more creative.

When we spend time outside
in beautiful places,

a part of our brain called the subgenual
prefrontal cortex quiets down.

And this is a part of the brain

that's associated with negative
self-involved thoughts.

A researcher at Stanford
made the nature connection

when he sent a group
of subjects to go walk

in a beautiful park
in Palo Alto for 90 minutes,

and he sent another group
to go walk in a city street,

and then he imaged their brains.

And it was only the people
who walked in the park

who experienced this beneficial change.

So nature can be so helpful
to us in so many ways.

It can also make us creative
in small doses.

For example, here's Facebook,

and hi-tech communities
all over are now figuring out

that if they incorporate green roofs
and trails into their very structures,

that this can benefit their business.

We've known this for a long time.

Everyone from Aristotle to Beethoven,

to Darwin, the Brontë sisters,
Wordsworth, Einstein,

the list goes on and on,

so many people attribute
walking in these beautiful spaces

to being critical
to their creative process.

What happens, though, when we spend
even more time in nature,

as far as our brains and our psychology?

We know that physiological changes happen,

which we saw with
the natural killer cells.

But what happens
on a more psychological level?

This was something I was fascinated
to actually witness,

when I met a woman named Tania Herrera.

She had just returned
from two tours of Iraq,

and she'd been badly injured in rocket
grenade fire and also by a car bomb.

She'd experienced a bad concussion,
she'd lost the use of one of her arms.

She experienced seizures, 
anxiety, depression.

She had trouble performing
simple tasks and even reading.

She never wanted to leave her house,

because she felt like
she was a prisoner in her own body.

But when she'd been young, 
she'd participated in a program

to take inner-city kids out into nature.

And she'd remembered
that that had given her some comfort.

So she signed up for a six-day river trip
down the Salmon River in Idaho.

She and her other fellow warriors
on this trip paddled and swam,

and slept under stars and talked
in the camp, around the campfire.

And I had the privilege of watching
them emerge from cocoons of sadness

to full-bodied full-sensory survivors
helping each other,

relishing their new friendships
and the possibilities ahead.

She said to me:

"When I'm home I feel overwhelmed,
there's nothing to brace on,

and I'm overwhelmed
by bad thoughts and feelings.

When I'm out here life is simple,
there's something to brace on,

there are good thoughts,
there is balance."

Wilderness advocate John Muir understood
the power of wilderness

to help heal our psyches.

He wrote:

"Between every two pine trees, there is
a door leading to a new way of life."

There is a simple recipe to improve
the quality and meaning of our days.

And it's to open Muir's door.

Go outside, go often.

Thank you.

(Applause)