The 80s were all about big hair, neon, MTV.

And then there was this:

"Every October a hole appears in the ozone layer over the south pole."

"...hole in the ozone shield is the size of the continental United States."

"The protective ozone layer is being threatened as never before."

"We are all at risk."

Scientists warned that humanity was on track to completely destroy the ozone layer by 2050.

Without it ecosystems would collapse,

skin cancer rates would skyrocket,

and life as we knew it would cease to exist.

But today, the ozone layer is healing.

In an unprecedented act, the world came together to prevent an environmental catastrophe.

So how did we do it?

And what can we learn from it?

The ozone layer is a sort of “belt” around the Earth made up of gaseous molecules.

It protects every living thing

by absorbing two types of ultraviolet radiation from the Sun.

It's a powerful shield, but it's also fragile.

In 1985, scientists discovered a massive loss of ozone here:

right over Antarctica.

40% of the layer had dissipated, creating a “hole”.

Scientists realized the hole formed in the spring and every year it got worse.

This was a wake up call.

It wasn't small and far in the future.

It was now and way bigger than anybody ever imagined.

That's Dr. Solomon, an atmospheric chemist.

In 1986, she flew to Antarctica, along with other scientists

to investigate the cause of the ozone hole.

“Leading the team is Susan Solomon,

a young atmospheric chemist from Boulder, Colorado."

You know once you step off the plane in Antarctica,

if you've never been there before,

your main goal is to get out without getting frostbite.

"Do you want to do the next one?"

But what really our goal was to take measurements,

not just of ozone, but also of different chemicals that would help to show why it was going away.

Some scientists released balloons in the sky to take ozone measurements.

While others took measurements on the ground.

And they all came to the same conclusion.

The biggest problem was chlorine from a man-made compound called Chlorofluorocarbons, or CFCs.

On the ground CFCs aren't harmful.

But once they float up to the stratosphere the Sun breaks them down into chlorine.

They bind with ozone to make oxygen and chlorine monoxide.

Then the loose oxygen atoms bump the chlorine atom out,

freeing it to destroy more ozone molecules.

And that causes a chain reaction.

The long lifetime of the chlorofluorocarbons is a big part of the problem.

They live anywhere between 50 and 150 years in our atmosphere so...

It means that every year that you use

what you use the year before is almost entirely still there.

So it just builds up and builds up exponentially.

And back then we used a lot of CFCs.

The US had already moved away from CFCs in aerosol cans.

But most of the world hadn't yet.

And they were still in everything from refrigerators and air conditioners and styrofoam.

The entire world needed to make a big change quickly or we'd face--

Catastrophe.

Catastrophe.

Unmitigated catastrophe.

In 1987, ozone levels had dropped by 50 percent.

This growing threat led to some of the fastest collective action on climate we've ever seen.

So I like to think of it as, there's three P's that when, they're met we do very well

at addressing environmental problems.

So it was personal.

It was perceptible and the solutions were practical.

If you've been sunburned, you know that skin cancer is not a good thing.

So everybody understands skin cancer.

The personal nature of the threat is huge.

The perceptible was easy to do with satellite measurements.

You can just watch it get completely destroyed and go to zero

where there should have been a lot of ozone.

And we have practical solutions.

It was easy to find substitutes for chlorofluorocarbons in spray cans that took,

you know, less than a year to do.

It was a very straightforward switch,

And I think the main unifying factor in all of that is the public.

Scientists like Dr. Solomon held press conferences to inform the public.

"I think we will eventually see large scale depletions of the ozone layer in other latitudes."

The ozone hole started showing up in TV shows and movies.

“It's those damn fluorocarbons, they've been kicking the hell out of the ozone.”

“Macaroni, it will burn off.”

“Well so will the ozone, eventually.”

And all this public awareness put pressure on leaders around the world to act.

“We are here today because we recognize that urgent action is necessary.”

And the Montreal Protocol made it official.

It recognized “that world-wide emissions can significantly deplete the ozone layer

and result in adverse effects on human health and the environment."

It listed control measures to reduce ozone depleting substances in a series of steps.

Including help for developing countries

who need alternative technology and substituting products.

Every single country eventually signed the protocol.

Making it the only universal treaty to ever be ratified.

And the most successful environmental agreement in human history.

Soon after, the world's largest CFC producer began to phase them out.

Since the protocol went into effect on January 1st, 1989

the consumption of ozone-depleting substances

including CFCs, plummeted.

Today, more than thirty years after the Montreal Protocol was signed

the ozone hole has stopped growing and is now shrinking.

And by 2065 it is expected to have recovered completely.

But there's more to be done.

After the CFC ban we began using Hydrofluorocarbons or HFCs.

HFCs don't deplete the ozone layer but they are a potent greenhouse gas

that contributes to climate change.

And it's the fastest growing one.

So in 2016, the Montreal Protocol was amended to include HFCs

and now they are being phased out too.

But they are only one part of a larger issue.

"Climate change is already happening, right here, right now."

"Experts say that we have until 2030 to avoid catastrophe."

"People are suffering."

"People are dying."

"Entire ecosystems are collapsing."

"Unprecedented and even irreversible changes are happening to this planet."

"It is beyond any doubt that human activity is to blame."

Climate change, our most challenging environmental problem is still in need of big solutions.

So I think people in most parts of the world, now understand

and are concerned about, the personal impact.

They found it to be perceptible.

And we are finding practical solutions.

It's not true that we can't do it anymore.

We need to keep our eye on the ball on climate change.

And if we do we will get the environment that we demand.