The problem of light pollution -- and 5 ridiculously easy ways to fix it

Unless you've spent quality time
on the International Space Station,

this is probably not a view
you are super familiar with.

This is the east coast
of the United States.

That's New York down there
in the lower right,

and it's a band of light
all the way up through Washington DC.

Those cities are shining like jewels,

highways are traced by webs of light.

And all of that light is super photogenic.

But there's a problem.

That light is meant to be
illuminating our sidewalks,

and our streets and our houses.

Instead, it's actually
going up into the sky

and out into the universe,

where it's doing any of us any good.

When I see photos of this, of the Earth,

I see environmental catastrophe.

Those aren't jewels,

those are tumors.

I'm an astronomer,

so it's really no surprise
probably to anyone

that I've always loved the night sky.

I'm kind of a walking cliche.

But when I was growing up in Minnesota,

one of my favorite things to do
on a summer evening

was grab my old Raggedy Ann sleeping bag

and take it out into a field
behind my house,

where I would spend hours
looking at the night sky.

And to do this, I had to brave
not only the darkness,

but also swarms of mosquitoes,

and my sleeping bag
really didn't smell very good.

(Laughter)

But there was one particular star

that I would look for, night after night.

And then I would play this game

where I would try to focus
on that star so intensely,

that everything else
would fade from my view

and that single star
would be all that I could see.

I could only ever hold on to that focus

for a few fleeting moments.

But when I did,

I felt this deep sense
of connection to the universe.

And almost a sense of vertigo,

like I was going to fall into space.

And when this happened --

I know this sounds kind of ridiculous,

but I would simultaneously feel
unfathomably insignificant

and also kind of weirdly important.

That star I looked to
night after night, was called Vega.

Vega is the brightest star
in the constellation Lyra,

which is not coincidentally
the name of one of my dogs.

(Laughter)

But this experience is being lost.

My favorite constellation, Lyra,

this is what it would look like
from Manhattan.

For people who live in urban
and suburban environments,

if they go outside at night and look up,

instead of being awestruck
by the majesty of the universe,

they see pretty much nothing.

These unremarkable,
completely blank night skies,

of course are due to all of the light
we produce at night.

Those very same lights
we see all the way from space

are shining up into the atmosphere,

where they bounce around
and create this featureless smog of light.

And that featureless
smog of light has a name.

It's called light pollution.

As an astronomer,

I can actually tell
how bad light pollution is

by the brightness of stars
I can see in the sky.

And it turns out

that when you're trying to unlock
the secrets of the cosmos,

it's really helpful
to be able to see the cosmos.

And --

Truth.

And this light that we're trying to detect

is coming from millions or billions
of light years away,

and so it's generally pretty faint.

And as an astronomer,

I fight with this every day to do my job,

and I have to tell you,
it is a really big problem.

But the problem is far worse

than just losing some
whimsical ability to gaze at the stars.

For example,

countless plant and animal
species are affected.

So we could talk about sea turtles

or pollinators

or any of these super important species

that are also cute.

Instead, I want to talk

about these quietly unassuming dog whelks.

You may have seen them around

and not given them
really a whole lot of thought.

But they're pretty cool.

So in an entire year

a dog whelk will rarely move
more than about 10 metres.

That means that when
they are attacking their prey

they can hit this brisk pace
of about a millimeter an hour.

And --

(Laughter)

This works out OK,

because they attack things like barnacles.

(Laughter)

So these dog whelks live
in the intertidal area of coasts,

where, it turns out,

they're a pretty key part
of the ecosystem.

Not only are they one of the most
dominant invertebrate predators,

but other animals, like crabs and birds,
think they're pretty tasty.

So that leaves these poor snails
in a kind of precarious situation,

because if they go too low in the water

then crabs are a threat,

but if they come out of the water too far,

birds are going to have a feast.

Why is an astronomer
telling you about dog whelks?

I ask that myself.

Because their behavior
is impacted by light pollution.

For example,

if dog whelks are subjected
to artificial light at night

they're about twice as likely
to stay under the water with a predator.

And that puts them at increased risk.

And it's not like they can make
a speedy escape.

And so these --

(Laughter)

And the other issue
is because they literally move

at a snail's pace.

If a population is wiped out,

it can take decades to replenish.

And that, in turn, affects
the rest of their ecosystem

and the other species, like the birds
and the barnacles and the crabs.

So this is just one
small and slimy example

of how light pollution
can unleash a cascade effect

on an entire ecosystem.

Virtually every species
that has been studied to date

is impacted by light pollution.

And that includes humans.

So let's talk about us.

You are probably not surprised to hear

that light pollution can affect
your ability to sleep well at night.

But you might be surprised to hear
that light pollution is linked to obesity.

In fact, in a recent study

they found that light pollution
contributed to over 70 percent

of the obesity rates in 80 countries.

More than that,

light pollution actually contributed
about the same amount to excess weight

as eating junk food.

And it gets worse.

For people who are subjected

to significant amounts
of artificial light at night

they're about 50 percent more likely
to get breast cancer.

And in fact, light pollution
is correlated with types of cancer

across the board.

And in controlled lab experiments

there's a direct link between
increased artificial light at night

and a rate of tumor growth.

You might be wondering how normal light

could possibly impact cancer rates.

It likely all comes down
to the super important hormone

called melatonin,

which we have evolved
over millions of years

to produce on a day-night cycle
or a circadian rhythm.

What happens is that when light impacts

the retina at the back of our eye at night

it can disrupt melatonin production,

and when melatonin
production is disrupted,

a whole chain of other
chemical processes are affected,

and that includes estrogen production.

And when we throw
this chemical balance out of whack,

really bad things can happen.

In fact, things are so bad,

that the International Agency
for Cancer Research

has said that disrupting
the human circadian rhythm

is a probable carcinogen.

Also, for fun, I want to let you know

that light pollution has been linked to,

let's see -- headaches, anxiety,
depression, diabetes,

cardiovascular disease
and the list goes on.

But maybe you don't care
about your health.

We're all going to die anyway,

you might as well die
in a brightly-lit room.

(Laughter)

The fact that you're laughing
about death is kind of amazing.

(Laughter)

You might still care about money.

The money that's spent
on that wasted light,

and I mean just the light
that's going out into the universe,

and not doing us any good,

is three billion dollars a year.

That's enough money to build, like,

1,000 utility-grade windmills,

or fund the entire DC public-school
system for over two years,

or -- this is my favorite,
because I really want one

but I can't afford one --

buy 30,000 Tesla Model X SUVs.

(Laughter)

And that includes
the electric car tax credit.

And then there are the existential costs.

I don't have any data

on how losing touch
with our place in the cosmos

impacts us.

But I believe

that this probably impacts our humanity

more than any of the other
scary statistics I can share with you.

And it's getting worse with time.

The amount of light pollution
is doubling roughly every 35 years.

That means that within the next decade

virtually the entire eastern half
of the United States

will be perpetually brighter
than twilight.

And there's another issue
with light pollution.

The problem is way worse
than we can see with our own eyes.

Our eyes have evolved
to just detect this tiny range

of the full spectrum of light.

All of this other light that we can't see,

this invisible light,

also has a pollution problem.

Mostly it's from modern technology,

things like cell phones
or car-to-car radar,

or now apparently we need appliances
that can talk to each other.

All of this modern technology
is putting out strong signals

that can completely swamp

these exceedingly faint light
we're trying to detect

from the rest of the universe
outside Earth,

which just for the record,
is most of the universe.

(Laughter)

And then, there are satellites.

Satellites are a problem at both
visible and invisible wavelengths.

A host of private companies have plans
to deploy tens of thousands of satellites

into Earth orbit,

where they will not only outnumber,

literally outnumber
the visible stars in the sky,

while also beaming
invisible light back to Earth.

So for astronomers like me,

who use invisible light
to study the universe,

it's going to be like staring at the Sun

and trying to see
a birthday candle behind it.

Alright, I want to be clear

that there's nothing inherently wrong
with any of this modern technology.

With cell phones
or satellites or car radar.

I'm not sure about kitchen appliances.

(Laughter)

I haven't broken down

and gotten an oven
that talks to my cell phone yet.

And I use lights at night
like everybody else.

But here's the thing.

Some problems in the world,

like we've heard about today
and you'll hear more about,

are overwhelming
and they seem intractable.

Visible light pollution
is not one of these problems.

This is actually stupidly simple, OK.

So here are five
super simple things you can do.

Don't use lights
brighter than you need to.

Don't use lights when you don't need them.

Those lights you're using,

make sure they're shielded down,

so they're no shining up into the sky.

And let's talk about LED lights.

If you have a choice,
don't buy the blue ones.

Look for words like "warm white."

If you buy LEDs with words like
"natural light" or "daylight,"

that's like saying you hate space.

(Laughter)

And finally,

you could advocate for this.

Even in your local community,

find out if there's a lighting code

and whether it could be made
more night-sky-friendly.

Or dare I say, you could even advocate
at the federal level,

by politely asking our federal officials,

some of whom may be here,

to please not auction off
our view of the invisible universe

to the highest bidder to pollute at will,

which is actually what happens.

Now, like a good professor,

I have homework for you.

If you have never seen
a truly dark night sky,

I want you to go out
and experience one for yourself.

Because if you don't,

you don't know what you're missing,

and you don't know
what humanity is losing.

Thank you.

(Applause)