Let's scan the whole planet with LiDAR

We have archives of films, newspapers, even seeds -- what if we could make one for the entire surface of the earth? Drawing on his experience mapping an ancient city in the Honduran jungle, archaeologist Chris Fisher makes the case for scanning the whole planet with LiDAR -- a technology that uses lasers shot from an airplane to map the ground -- in order to preserve our cultural and ecological heritage.

The most astounding place I've ever been
is the Mosquitia Rain Forest in Honduras.

I've done archaeological fieldwork
all over the world,

so I thought I knew what to expect
venturing into the jungle,

but I was wrong.

For the first time
in my life, I might add.

(Laughter)

First of all, it's freezing.

It's 90 degrees, but you're
soaking wet from the humidity,

and the canopy of trees is so thick
that sunlight never reaches the surface.

You can't get dry.

Immediately, I knew that
I hadn't brought enough clothing.

That first night, I kept feeling things
moving underneath my hammock,

unknown creatures brushing and poking
against the thin nylon fabric.

And I could barely sleep
through all the noise.

The jungle is loud. It's shockingly loud.

It's like being downtown
in a bustling city.

As the night wore on,

I became increasingly frustrated
with my sleeplessness,

knowing I had a full day ahead.

When I finally got up at dawn,

my sense of unseen things
was all too real.

There were hoofprints, paw prints,

linear snake tracks everywhere.

And what's even more shocking,

we saw those same animals in the daylight,

and they were completely unafraid of us.

They had no experience with people.

They had no reason to be afraid.

As I walked toward the undocumented city,
my reason for being there,

I realized that this was the only place
that I had ever been

where I didn't see
a single shred of plastic.

That's how remote it was.

Perhaps it's surprising to learn

that there are still places on our planet
that are so untouched by people,

but it's true.

There are still hundreds of places
where people haven't stepped for centuries

or maybe forever.

It's an awesome time
to be an archaeologist.

We have the tools and the technology

to understand our planet
like never before.

And yet, we're running out of time.

The climate crisis threatens to destroy
our ecological and cultural patrimony.

I feel an urgency to my work

that I didn't feel 20 years ago.

How can we document everything
before it's too late?

I was trained as
a traditional archaeologist

using methodologies that
have been around since the '50s.

That all changed in July of 2009

in Michoacán, Mexico.

I was studying the ancient
Purépecha Empire,

which is a lesser known
but equally important contemporary

of the Aztec.

Two weeks earlier, my team
had documented an unknown settlement,

so we were painstakingly mapping,
building foundations by hand --

hundreds of them.

Basic archaeological protocol
is to find the edge of a settlement

so you know what you're dealing with,

and my graduate students
convinced me to do just that.

So I grabbed a couple of CLIF Bars,
some water, a walkie,

and I set out alone on foot,

expecting to encounter "the edge"
in just a few minutes.

A few minutes passed.

And then an hour.

Finally, I reached
the other side of the malpais.

Oh, there were ancient
building foundations all the way across.

It's a city?

Oh, shit.

(Laughter)

It's a city.

Turns out that this
seemingly small settlement

was actually an ancient urban megalopolis,

26 square kilometers in size,

with as many building foundations
as modern-day Manhattan,

an archaeological settlement so large

that it would take me
decades to survey fully,

the entire rest of my career,

which was exactly how I didn't want
to spend the entire rest of my career --

(Laughter)

sweating, exhausted,

placating stressed-out
graduate students --

(Laughter)

tossing scraps of PB and J sandwiches

to feral dogs,

which is pointless, by the way,

because Mexican dogs
really don't like peanut butter.

(Laughter)

Just the thought of it bored me to tears.

So I returned home to Colorado,

and I poked my head
through a colleague's door.

"Dude, there's gotta be a better way."

He asked if I had heard
of this new technology called LiDAR --

Light Detection And Ranging.

I looked it up.

LiDAR involves shooting
a dense grid of laser pulses

from an airplane to the ground's surface.

What you end up with
is a high-resolution scan

of the earth's surface
and everything on it.

It's not an image,

but instead it's a dense,
three-dimensional plot of points.

We had enough money in the scan,

so we did just that.

The company went to Mexico,

they flew the LiDAR

and they sent back the data.

Over the next several months, I learned
to practice digital deforestation,

filtering away trees, brush
and other vegetation

to reveal the ancient
cultural landscape below.

When I looked at my first visualization,

I began to cry,

which I know comes
as quite a shock to you,

given how manly I must seem.

(Laughter)

In just 45 minutes of flying,

the LiDAR had collected
the same amount of data

as what would have taken decades by hand:

every house foundation,

building, road and pyramid,

incredible detail,

representing the lives
of thousands of people

who lived and loved and died
in these spaces.

And what's more, the quality of the data

wasn't comparable to traditional
archaeological research.

It was much, much better.

I knew that this technology would change
the entire field of archaeology

in the coming years,

and it did.

Our work came to the attention
of a group of filmmakers

who were searching for a legendary
lost city in Honduras.

They failed in their quest,

but they instead documented
an unknown culture,

now buried under a pristine
wilderness rain forest,

using LiDAR.

I agreed to help interpret their data,

which is how I found myself deep
in that Mosquitia jungle,

plastic-free and filled
with curious animals.

Our goal was to verify
that the archaeological features

we identified in our LiDAR

were actually there on the ground,

and they were.

Eleven months later, I returned
with a crack team of archaeologists

sponsored by the
National Geographic Society

and the Honduran government.

In a month, we excavated over 400 objects

from what we now call
the City of the Jaguar.

We felt a moral and ethical responsibility
to protect this site as it was,

but in the short time that we were there,

things inevitably changed.

The tiny gravel bar where we first
landed our helicopter was gone.

The brush had been cleared away
and the trees removed

to create a large landing zone
for several helicopters at once.

Without it,

after just one rainy season,

the ancient canals that we
had seen in our LiDAR scan

were damaged or destroyed.

And the Eden I described
soon had a large clearing,

central camp,

lights

and an outdoor chapel.

In other words, despite our best efforts
to protect the site as it was,

things changed.

Our initial LiDAR scan
of this City of the Jaguar

is the only record of this place
as it existed just a few years ago.

And broadly speaking,

this is a problem for archaeologists.

We can't study an area
without changing it somehow,

and regardless, the earth is changing.

Archaeological sites are destroyed.

History is lost.

Just this year, we watched in horror

as the Notre Dame Cathedral
went up in flames.

The iconic spire collapsed,

and the roof was all but destroyed.

Miraculously, the art historian
Andrew Tallon and colleagues

scanned the cathedral in 2010 using LiDAR.

At the time, their goal was to understand
how the building was constructed.

Now, their LiDAR scan is the most
comprehensive record of the cathedral,

and it'll prove invaluable
in the reconstruction.

They couldn't have anticipated the fire

or how their scan would be used,

but we're lucky to have it.

We take for granted that our cultural
and ecological patrimony

will be around forever.

It won't.

Organizations like SCI-Arc
and Virtual Wonders

are doing incredible work

to record the world's historic monuments,

but nothing similar exists
for the earth's landscapes.

We've lost 50 percent of our rain forests.

We lose 18 million acres
of forest every year.

And rising sea levels will make cities,
countries and continents

completely unrecognizable.

Unless we have a record of these places,

no one in the future
will know they existed.

If the earth is the Titanic,

we've struck the iceberg,

everyone's on deck

and the orchestra is playing.

The climate crisis threatens to destroy
our cultural and ecological patrimony

within decades.

But sitting on our hands and doing nothing

is not an option.

Shouldn't we save everything
we can on the lifeboats?

(Applause)

Looking at my scans
from Honduras and Mexico,

it's clear that we need
to scan, scan, scan

now as much as possible,

while we still can.

That's what inspired the Earth Archive,

an unprecedented scientific effort

to LiDAR-scan the entire planet,

starting with areas
that are most threatened.

Its purpose is threefold.

Number one: create a baseline record
of the earth as it exists today

to more effectively mitigate
the climate crisis.

To measure change, you need
two sets of data:

a before and an after.

Right now, we don't have
a high-resolution before data set

for much of the planet,

so we can't measure change,

and we can't evaluate
which of our current efforts

to combat the climate crisis

are making a positive impact.

Number two: create a virtual planet

so that any number of scientists
can study our earth today.

Archaeologists like me
can look for undocumented settlements.

Ecologists can study tree size,

forest composition and age.

Geologists can study hydrology,

faults, disturbance.

The possibilities are endless.

Number three: preserve
a record of the planet

for our grandchildren's grandchildren,

so they can reconstruct and study
lost cultural patrimony in the future.

As science and technology advance,

they'll apply new tools, algorithms,

even AI to LiDAR scans done today,

and ask questions that we
can't currently conceive of.

Like Notre Dame,

we can't imagine how these
records will be used.

But we know that they'll
be critically important.

The Earth Archive is the ultimate gift
to future generations,

because the truth be told,

I won't live long enough
to see its full impact,

and neither will you.

That's exactly why it's worth doing.

The Earth Archive is a bet
on the future of humanity.

It's a bet that together,

collectively,

as people and as scientists,

that we'll face the climate crisis

and that we'll choose
to do the right thing,

not just for us today

but to honor those who came before us

and to pay it forward
to future generations

who will carry on our legacy.

Thank you.

(Applause)