A scientist’s first-hand account shows that the world can face a global environmental crisis.
As the plane roared through an unstable sky, I looked out the window at the landscape of shifting ice floes and the dark ocean. There were no roads, settlements, structures of any kind, not even the occasional lone ship in the seas of the south pole. As we approached the continent, the last rays of the sun faded, replaced by a blue and purple sunset. It was then that I realized that we were indeed on our way to the last outpost on Earth. Just the year before, I was happily sitting at my desk in the office, studying stratospheric chemistry using computer models. The key molecule in that chemistry is ozonea highly reactive gas produced from oxygen that has unique abilities to absorb high-energy ultraviolet light. Earth’s fragile ozone shield stands between us and the Sun’s rays and is what first allowed life to crawl out of the ocean and walk on land. A “layer” of ozone formed naturally in the stratosphere as oxygen evolved on Earth, about 15-50 kilometers above our heads.
A future problem
The United States National Ozone Expedition (or NOzE, as we called it) consisted of 16 scientists from four different research institutions. At 30 I was the youngest and only woman. Yet I was the lead scientist on the projectwhich made me the spokesperson for the group and, occasionally, the decision maker. I liked it more than I expected. I also gained a deep understanding of how politics works and the critical role of public opinion.
CFCs (chlorofluorocarbons) and other ozone-depleting chemicals have been banned everywhere under the most successful global environmental treaty the world has ever known (so far), and humanity has already put the ozone hole on the map. good way to heal slowly. It would take me decades to understand how and why this miracle of environmental cleanup happened.
That first flight to Antarctica wasn’t really the beginning of my journey: I had been studying the atmosphere for about a decade before heading south, and my personal work followed a long history of ozone research. Towards the end of the 19th century, scientists began to understand how the ozone layer protects us from the Sun.
The discovery of the ozone hole
The discovery of the ozone hole sent shockwaves through the global scientific community when it was made public in the journal Naturein May 1985. Many of my older colleagues were horrified by the publication. If it was true, why hadn’t the satellites picked it up?
It didn’t take long to solve that mystery. NASA scientists went back and rechecked their algorithms and reported within a few months that they had also seen Antarctic ozone changes, and that they were covering most of the continent. In the view from space, one could easily see that a huge hole in the ozone layer had formed. Satellite data could even be transformed into dramatic color video clips, in which a vortex with its ozone hole could be seen above the South Pole, rotating like a hurricane seen from space, a hurricane with a gaping hole instead of an eye.
When they got on TV and in the newspapers, the problem became public knowledge. If it had been proven to be due to chlorofluorocarbons, then it would have been a scientific crisis that people could perceive.
The best idea
Antarctica is also the coldest place in the stratosphere. Gaseous chlorofluorocarbons break down in the high-intensity light of the stratosphere and are converted mainly into hydrochloric acid and chlorine nitrate gas. As long as the chlorine stays there, the ozone is safe. And these two things don’t react together at all in the gas phase.
I started thinking about what might be happening on the surfaces of those freezing clouds. Surfaces can profoundly change chemistry; that’s why our gasoline cars have catalytic converters whose surfaces transform our exhaust gases into less dangerous compounds. I thought that hydrochloric acid and chlorine nitrate might come together and react on the surfaces of those polar cloud particles, releasing the ozone-destroying chlorine and returning it to the gas phase. This, along with the need for some sunlight (to drive further reactions), was the essence of my idea.
The Montreal Protocol
I presented the work to colleagues at a scientific conference in the same month. I remember well the skepticism with which my presentation was received, with a lot of difficult questions. But hard questions are what science is about, and they make our work stronger. It must be strong if people are to make industrial decisions or base policies on it.
Protection of the ozone layer through the 1987 Montreal Protocol it is rightly called the world’s greatest international environmental success story, celebrated globally and seen as proof of what people can achieve in managing environmental risk.
Signs of healing of the ozone hole
Can progress still happen when it does not depend on personal choices but on political ones? Certain. Getting rid of CFCs in refrigeration and air conditioning was not something the individual consumer could do, beyond limited personal choices. But technology-driven policies have inspired the innovation needed to find those solutions and make them cheap enough to be practical.
The discovery of the Antarctic ozone hole stunned the whole world and made the ozone issue a “hot crisis”. People are much better at solving hot crises. Public fascination has kept scientists energetic and politicians well motivated to act. Scientists have become accustomed to the fantastic power of teamwork: in field experiments to the ends of the Earth and, most importantly, in international evaluation reports. We stopped working as lone wolves and became an effective pack, knowing that as a group we could serve the world better than any of us could do alone.
The Antarctic ozone hole varies from year to year, affected by things like volcanic clouds and smoke from forest fires that can lead to a long-lasting hole for a year or two, until those extra particles disperse. But the signs of healing the damage we have caused are already clear in the long term. Can we continue like this? We will always have to be alert to new threats, whether it is, potentially, metal particles released from satellites or the growing number of leisure travel into space, so stay tuned.
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