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John: It's one of the great
environmental success stories of
our time.
Scientists say that a
35-year-old agreement has
resulted in the steady and
promising recovery of the
Earth's ozone layer.
Located in the stratosphere,
about 10 to 25 miles above the
Earth, the ozone layer is a
critical protective shield,
blocking the sun's harmful
ultraviolet radiation.
William brangham has more.
William: Back in 1987, after
scientists discovered a
dangerous thinning of the ozone
layer, 198 countries signed the
Montreal protocol, which largely
phased out the use of substances
that damaged that protective
barrier, like chemicals used in
aerosols or refrigeration.
Now, 35 years later, a recent
assessment by the U.N. Shows it
is steadily recovering.
In fact, much of the ozone layer
is on pace for nearly full
recovery by the year 2040.
Joining us now is Dr. Paul
Newman.
He's chief scientist for Earth
sciences at nasa's Goddard space
flight center and co-chair of
the assessment panel that
documented the ozone recovery.
Before we talk about the
recovery, can you just remind us
why we care about the ozone
layer, what what benefits it
provides to us humans and life
down here on Earth?
Dr. Newman: Sure.
Ozone is three atoms of oxygen,
and it is, most of it is located
many miles above our heads.
It screens harmful solar
ultraviolet radiation.
Ultraviolet radiation can break
the bonds of biologically active
molecules that can lead to
things like skin cancer and
cataracts.
So a healthy ozone layer is
necessary for life on Earth.
William: And so were we seeing
some of those impacts as the as
-- as the ozone thinned over the
years?
Dr. Newman: We saw a pretty
good, well, actually a very,
very strong depletion of ozone
over Antarctica, over the rest
of the Earth's surface, we saw a
thinning of a few percent, which
is not a terribly big deal,
because the Montreal protocol
captured the problem with ozone
depletion, and they acted to
curtail the production and
consumption of
chlorofluorocarbons and other
ozone depleting substances.
So the problem over most of the
year didn't get too bad.
William: So there has been this
steady evidence that it looks
like the protocol worked as
intended.
And now, this most recent
report, that you were a part of,
is really tremendous news.
I wonder what is the reaction
you've been hearing in the
scientific community?
Dr. Newman: I think the
scientific community has been
pretty aware of the progress of
things.
But to see it all
comprehensively, to know that
emissions of ozone depleting
substances are declining, to
know the levels of these ozone
depleting substances are going
down, we see methane, CO2 and
n20 going up but ozone depleting
substances are going down. And
now we see the increase of ozone
in the southern mid-latitudes,
the tropics and the northern
mid-latitudes.
This is good news for the
scientific community and for the
Earth as a whole.
William: Well, how how rare it
is we get to say that in this
world today.
What kind of tangible impacts --
you mentioned some of them, that
it might be a reduction in skin
cancer.
Are there other tangible impacts
for a repaired ozone layer for
us?
Dr. Newman: Sure.
Besides the health effects for
humans, crop yields.
Crops are damaged by uv
radiation.
Materials are actually degraded
by uv radiation.
Plants, other phytoplankton, for
example, are affected by uv
radiation. So this is, overall,
a very good story for life of
the Earth's surface.
We, as you might know, we use uv
to sterilize, for example,
medical instruments.
Getting a uv down here at the
surface is not a good thing. And
to see the ozone recovering is a
very nice thing to know about.
William: Is that all good news
in this report, or is there
anything in there that is
troubling to you?
Dr. Newman: There's a number of
things we continue to worry
about.
We need to continue to monitor
the ozone layer.
There are new technologies
coming on, for example, new
supersonic aircraft.
One would hope that they could
be designed and flown in an
ozone friendly manner.
And there's also more rocket
launches that are going on.
They deposit material into the
stratosphere.
We're worried about the
potential impacts of large
numbers of rocket launches, and
actually, the satellites as they
reenter the Earth's atmosphere.
What do they do to the ozone
layer?
So we worry about these things.
We also worry about rogue
production of ozone depleting
substances.
In fact, that happened in the
last few years, with
chlorofluorocarbons 11.
But the Chinese government acted
to curtail that, and it's come
back down to a more normal
level.
So we worry about it, we monitor
it, and hopefully, countries
continue to abide by the
Montreal protocol.
William: My understanding is
that targeting these particular
chemicals was somewhat easier
because there were safer
alternatives available for
industry. The other big
emissions that we're trying to
stop obviously, is carbon and
methane, as you were describing,
which drive climate change.
Targeting those emissions
obviously is a much steeper
climb for humanity, right?
Dr. Newman: It very much is a
steep climb.
People have gas stoves.
They have automobiles burning
fuels.
We have power plants burning
coal.
These are all CO2, carbon
dioxide producers
and solving the problem of
carbon emissions will be very
difficult.
That doesn't mean it can't be
done.
Every nation on the Earth has
signed on to the Montreal
protocol.
In all the political
differences, national
differences, every nation has
identified the ozone layer as
something that needs to be
watched and preserved, and
they've all signed on to the
Montreal protocol. So I'm
actually optimistic that
something will be done
eventually about climate and we
will cure this environmental
problem.
William: All right. Dr. Paul
Newman at nasa's Goddard space
flight center, thank you so much
for being here.
Dr. Newman: Thank you for having
me.