Can we solve global warming? Lessons from how we protected the ozone layer | Sean Davis

So, I'm a climate scientist, and if this room is representative
of the country we live in, that means about 60 percent of you,
so maybe from about there over, don't strongly trust me for information
on the causes of climate change. Now, I promise to tell the truth tonight, but just to humor that demographic, I've started this talk with a falsehood. [The Paris Climate Accord
is a product of the recognition that climate change
is a global problem …] This statement was not made
by President Obama. It was made by President Reagan, and it wasn't about climate change
and the Paris Climate Accord. It was actually
about the Montreal Protocol and stratospheric ozone depletion. Now, I'm sure that many of you aren't
familiar with this environmental problem, but you should be, because it's a rare
environmental success story.

And it's worth revisiting, because sometimes, we need
to examine the world we've avoided in order to find guidance
for the choices we make today. So let's go back to the 1970s, when some questionable choices were made: first of all — hoo —
hairstyles. (Laughs) Second of all, objectively
terrible quantities of hairspray, and third, CFCs, chlorofluorocarbons, man-made chemicals that were used
as propellant in aerosol spray cans. And see, it turns out
these CFCs were a problem because they were destroying
the ozone layer. Now I'm sure most of you
have heard of the ozone layer, but why does it matter? Well, quite simply,
the ozone layer is earth's sunscreen, and it's really fragile. If you could take all of the ozone, which is mostly about
10 to 20 miles up above our heads, and compress it down
to the surface of the earth, it would form a thin shell
only about two pennies thick, about an eighth of an inch. And that thin shell does
an amazing amount of work, though. It filters out more than 90 percent
of the harmful UV radiation coming from the sun. And while I'm sure many of you
enjoy that suntan that you get from the remaining 10 percent,
it causes a lot of problems: cataracts, damage to crops, damage to immune systems and also skin cancer.

It's not an exaggeration to say that a threat to the ozone layer
is a threat to human safety. And actually, ironically,
it was human safety that motivated the invention
of CFCs in the first place. You see, in the early days
of refrigeration, refrigerators used toxic
and flammable chemicals like propane and ammonia. For good reason,
the refrigeration industry wanted a safe alternative, and they found that in 1928, when a scientist named Thomas Midgley synthesized the first
commercially viable CFCs. And in fact, Midgley famously
inhaled CFCs and blew out a candle to demonstrate,
at a scientific conference, that they were safe and nonflammable. And in fact, as a scientist,
I can tell you there is no way you could get away
with that kind of antic today. I mean, wow. But really, at the time, CFCs were a really remarkable invention. They allowed what we now know
as modern-day refrigeration and air-conditioning and other things. So it wasn't actually until
over 40 years later, in the 1970s, when scientists realized that CFCs
would break down high in the atmosphere and damage the ozone layer.

And this finding really set off
a lot of public concern. It led, ultimately, to the banning
of CFC usage in aerosol spray cans in the US and a few
other countries in 1978. Now, the story doesn't end there, because CFCs were used
in much more than just spray cans. In 1985, scientists discovered
the Antarctic ozone hole, and this was a truly alarming discovery. Scientists did not expect this at all. Before the Antarctic ozone hole, scientists expected
maybe a five or 10 percent reduction in ozone over a century. But what they found
over the course of less than a decade was that more than a third of the ozone
had simply vanished, over an area larger
than the size of the US. And although we now know that CFCs
are the root cause of this ozone hole, at the time, the science
was far from settled.

Yet despite this uncertainty, the crisis helped spur nations to act. So that quote that I started
this talk with, about the Montreal Protocol,
from President Reagan — that was his signing statement
when he signed the Montreal Protocol after its unanimous ratification
by the US Senate. And this is something
that's truly worth celebrating. In fact, yesterday was the 30th
anniversary of the Montreal Protocol.

(Applause) Because of the protocol, ozone-depleting substances
are now declining in our atmosphere, and we're starting to see the first signs
of healing in the ozone layer. And furthermore, because many
of those ozone-depleting substances are also very potent greenhouse gases, the Montreal Protocol
has actually delayed global warming by more than a decade. That's just wonderful. But I think it's worth
asking the question, as we face our current
environmental crisis, global warming, what lessons can we learn from Montreal? Are there any? I think there are. First, we don't need
absolute certainty to act. When Montreal was signed, we were less certain then
of the risks from CFCs than we are now of the risks
from greenhouse gas emissions.

A common tactic that people
who oppose climate action use is to completely ignore risk
and focus only on uncertainty. But so what about uncertainty? We make decisions in the face
of uncertainty all the time, literally all the time. You know, I'll bet those of you
who drove here tonight, you probably wore your seat belt. And so ask yourself, did you wear your seat belt
because someone told you with a hundred percent [certainty] that you would get
in a car crash on the way here? Probably not. So that's the first lesson. Risk management and decision making
always have uncertainty. Ignoring risk and focusing
only on uncertainty is a distraction. In other words, inaction is an action. Second, it takes a village
to raise a healthy environment.

The Montreal Protocol wasn't just
put together by industry and governments or environmental advocacy
groups and scientists. It was put together by all of them. They all had a seat at the table, and they all played
an important role in the solution. And I think in this regard, we're actually seeing
some encouraging signs today. We see not just environmental groups
concerned about climate change but also civic and religious groups, the military and businesses. So wherever you find yourself
on that spectrum, we need you at the table, because if we're going
to solve global warming, it's going to take actions at all levels, from the individual to the international and everything in between. Third lesson: don't let the perfect
be the enemy of the good. While Montreal has become the brake pedal
for stopping ozone depletion, at its beginning, it was more
just like a tap on the brakes. It was actually the later
amendments to the protocol that really marked the decision
to hit the brakes on ozone depletion. So to those who despair that the Paris Climate Accord
didn't go far enough or that your limited actions on their own
won't solve global warming, I say don't let the perfect
be the enemy of the good.

And finally, I think it helps us
to contemplate the world we've avoided. Indeed, the world we have avoided
by enacting the Montreal Protocol is one of catastrophic changes to our environment
and to human well-being. By the 2030s, we'll be avoiding millions
of new skin cancer cases per year with a number that would only grow. If I'm lucky, I'll live long enough
to see the end of this animation and to see the ozone hole
restored to its natural state. So as we write the story
for earth's climate future for this century and beyond, we need to ask ourselves,
what will our actions be so that someone can stand on this stage in 30 or 50 or a hundred years to celebrate the world
that they've avoided. Thank you. (Applause).

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