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Speaker 1: This Day in History Class is a production of iHeartRadio.

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Speaker 1: Hello and Welcome to This Day in History Class, a

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Speaker 1: show that demystifies history one day at a time. I'm

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Speaker 1: Gabe Lucier, and in this episode, we're talking about how

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Speaker 1: a scary discovery ultimately led to one of the greatest

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Speaker 1: environmental success stories of the modern age. The day was

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Speaker 1: May sixteenth, nineteen eighty five. The discovery of the Antarctic

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Speaker 1: ozone hole was first reported in the scientific journal Nature.

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Speaker 1: The landmark paper was written by three scientists from the

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Speaker 1: British Antarctic Survey, Joe Farman, Brian Gardner and Jonathan Shanklin.

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Speaker 1: Using a device called adopsin spectro photometer, the team had

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Speaker 1: been able to analyze the amount of ozone over the

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Speaker 1: South Pole, and the results were not good. The ozone

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Speaker 1: levels they detected were abnormally low in recent years, indicating

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Speaker 1: severe damage to the Earth's atmosphere and a palpable risk

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Speaker 1: to everyone who lived within it. Ozone, also known as trioxygen,

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Speaker 1: is an inorganic molecule that absorbs ultraviolet radiation. It's mostly

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Speaker 1: found in the planet's stratosphere, a layer of the atmosphere

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Speaker 1: between four and thirty miles above the surface. The part

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Speaker 1: of the stratosphere with the highest concentration of ozone gas

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Speaker 1: is called the ozone layer, and it acts as a

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Speaker 1: kind of invisible shield for the planet. That's because it

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Speaker 1: absorbs nearly all of the Sun's medium frequency UV rays,

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Speaker 1: harmful radiation that would otherwise reach the Earth's surface and

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Speaker 1: do serious damage to plants, animals, and humans. Put simply,

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Speaker 1: without the filtering effects of the ozone layer, life on

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Speaker 1: Earth would not be possible. That grim reality was likely

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Speaker 1: top of mind for the three scientists who found a

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Speaker 1: hole in the ozone layer. The organization they worked for,

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Speaker 1: the British Antarctic Survey, had been monitoring the ozone layer

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Speaker 1: since the late nineteen fifties, but no one realized it

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Speaker 1: was thinning until decades later. Farman, Gardener, and Shanklin finally

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Speaker 1: discovered the problem after noticing a drop in ozone concentrations

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Speaker 1: above Antarctica over the course of several years. They compared

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Speaker 1: the measurements of recent years with those of decades past

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Speaker 1: and found that ozone values had actually been dropping steadily

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Speaker 1: since the mid nineteen seventies. The team's conclusion was that

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Speaker 1: something in the stratosphere was destroying the ozone and had

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Speaker 1: an alarm rate too. According to the data, the Antarctic

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Speaker 1: ozone hole had formed in less than a decade and

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Speaker 1: was growing larger each year. The speed of the ozone

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Speaker 1: depletion pointed to human activity as the culprit, and thanks

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Speaker 1: to prior research, the bas scientists had a pretty good

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Speaker 1: idea of where to lay the blame. A decade earlier,

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Speaker 1: in nineteen seventy four, scientists Mario Molina and F. Sherry

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Speaker 1: Roland published a paper theorizing that chlorofluorocarbons, or CFCs, could

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Speaker 1: be harmful to Earth's ozone layer. The chemicals in question

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Speaker 1: had always been considered harmless. In fact, they were widely

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Speaker 1: used in all kinds of household appliances and products. Molina

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Speaker 1: and Roland suggested there was a hidden environmental danger to CFCs,

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Speaker 1: but at the time few people believed them. Large corporations

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Speaker 1: aggressively disputed the claims, insisting their products weren't harmful to

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Speaker 1: the environment. Some scientists contested the claims as well, while

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Speaker 1: others minimized them, claiming that if there was ozone depletion,

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Speaker 1: it would be minor and would only worsen over the

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Speaker 1: course of centuries, if not longer. Once the idea of

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Speaker 1: caution had been fully tossed aside, the use of CFCs

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Speaker 1: grew exponentially, and so too did the damage to the

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Speaker 1: ozone layer. Products with CFCs were sold all over the world,

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Speaker 1: and when those products were used, the chlorofluorocarbons they contained

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Speaker 1: were released into the atmosphere. The chemicals would then get

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Speaker 1: trapped in clouds which form over the Antarctic during polar winter.

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Speaker 1: Then when sunlight returned each spring, the rays would trigger

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Speaker 1: catalytic reactions in the airborne CFCs, and a small amount

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Speaker 1: of ozone would be burnt up in the process. The

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Speaker 1: accumulation and destruction of ozone and CFCs was a cycle

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Speaker 1: that played out each year, but when humans began releasing

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Speaker 1: more CFCs than ever before, we started burning off ozone

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Speaker 1: at a faster rate than it could be replenished. In fact,

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Speaker 1: it was later determined that those springtime reactions between the

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Speaker 1: mid nineteen seventies and eighties had destroyed ozone at a

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Speaker 1: rate of about one percent per day. The BSA's findings

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Speaker 1: were published in the Nature Scientific Journal in May of

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Speaker 1: nineteen eighty five. Not only did the team's paper present

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Speaker 1: evidence of the ozone hole's existence. It also suggested a

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Speaker 1: link to CFCs. NASA backed those claims a few months later,

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Speaker 1: after one of its atmospheric scientists captured satellite imagery that

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Speaker 1: clearly showed the ozone hole. Other researchers later confirmed that

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Speaker 1: CFCs were indeed responsible for the annual depletion of ozone.

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Speaker 1: The news came as vindication for the work of scientists

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Speaker 1: Molina and Roland, both of whom were eventually awarded the

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Speaker 1: nineteen ninety five Nobel Prize in Chemistry. Still, for everyone

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Speaker 1: else on the planet, confirmation of a gaping hole in

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Speaker 1: the ozone layer was pretty bad news. The ozone depletion

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Speaker 1: was happening much faster than anyone could have guessed, and

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Speaker 1: the bigger the whole grew, the more dangerous it would

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Speaker 1: become due to the increased levels of radiation that would

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Speaker 1: pass through it. Scientists projected that if the whole were

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Speaker 1: allowed to grow unchecked, there would be a drastic rise

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Speaker 1: in skin cancer and cataracts, as well as a severe

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Speaker 1: disruption of plant growth and a steep decline in marine

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Speaker 1: life reproduction. The threat of rampant disease and dwindling food

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Speaker 1: sources spurred the international community to take action in a

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Speaker 1: way rarely seen before or since. The uncharacteristically proactive response

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Speaker 1: was likely due to the relative ease with which the

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Speaker 1: problem could be solved. All we had to do was

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Speaker 1: stop producing and using CFCs, of far simpler prospect than

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Speaker 1: giving up something like fossil fuels, for instance. It was

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Speaker 1: so feasible, in fact, that just two years after ozone

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Speaker 1: depletion was brought to the world's attention, forty six nations

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Speaker 1: pledged to phase out the substances known to cause it.

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Speaker 1: The agreement was called the Montreal Protocol, and it included

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Speaker 1: steps to control, reduce, and eventually eliminate the production and

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Speaker 1: use of CFCs and other ozone depleting chemicals. Former UN

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Speaker 1: Secretary General Kofi Annon famously described the protocol as quote

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Speaker 1: the single most successful international agreement to date, and all

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Speaker 1: these years later, it's hard to argue with him. The

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Speaker 1: Montreal Protocol was ultimately signed by all one hundred and

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Speaker 1: ninety seven members of the United Nations, making it the

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Speaker 1: first treaty in the organization's history to be adopted unanimously.

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Speaker 1: As a result of that worldwide cooperation, scientists now predict

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Speaker 1: that the ozone layer will return to its pre nineteen

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Speaker 1: eighty levels before the end of the twenty first century.

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Speaker 1: It'll take that long for the ozone layer to replenish

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Speaker 1: itself because CFCs tend to have a rather long lifespan,

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Speaker 1: with some persisting in the atmosphere for up to one

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Speaker 1: hundred and fifty years. So even though ninety eight percent

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Speaker 1: of ozone depleting chemicals were phased out of production by

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Speaker 1: two thousand and nine, there are plenty of older ones

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Speaker 1: still up there destroying ozone. As we speak in the

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Speaker 1: grand scheme of things, one hundred years is a pretty

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Speaker 1: rapid recovery. But don't forget that century long healing process

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Speaker 1: is in response to a wound that only took humans

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Speaker 1: about a decade to self inflict. That unbalanced equation is

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Speaker 1: a big reason why experts are so concerned about climate change.

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Speaker 1: Humans have been contributing to global warming for far longer

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Speaker 1: than it took us to punch a hole in the

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Speaker 1: ozone layer, and we haven't been nearly as resolute about

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Speaker 1: changing our harmful behavior. The to that problem, if it's

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Speaker 1: not too late already, will be much more difficult than

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Speaker 1: finding alternatives to CFC's but if the Montreal Protocol teaches

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Speaker 1: us anything it's that where there's a will, there's a way.

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Speaker 1: That said the clock is ticking, so here's hoping we

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Speaker 1: find that will sooner rather than later. I'm Gabe Bluesier

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Speaker 1: and hopefully you now know a little more about history

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Speaker 1: today than you did yesterday. If you'd like to keep

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Speaker 1: up with the show, you can follow us on Twitter, Facebook,

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Speaker 1: and Instagram at TDI HC Show, and if you have

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Speaker 1: any comments or suggestions, you can always send them my

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Speaker 1: way by writing to This Day at iHeartMedia dot com.

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Speaker 1: Thanks to Chandler Mays and Ben Hackett for producing the show,

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Speaker 1: and thanks to you for listening. I'll see you back

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Speaker 1: here again tomorrow for another day in History Class