‘Let’s not give up now, we are on the cusp of success’

Susan Solomon was born and raised in Chicago and received her PhD in atmospheric chemistry from the University of California, Berkeley. She is known for her work from the 1980s that identified how the Earth’s protective ozone layer was being depleted by man-made chemicals. Her studies formed the basis of the 1989 Montreal Protocol – an international agreement that helped eliminate 99% of these harmful solvents. Solomon is now a professor of environmental studies and chemistry at MIT and has written three books, the latest of which is: Soluble: How We Healed the Earth and How We Can Do It Againapplies lessons from past environmental successes to the climate crisis.

What made you interested in science?
Simple answer: Jacques Cousteau – I thought this was the most incredible thing I had ever seen. But then I didn’t really like biology, and I liked chemistry. When I started reading about planetary atmospheres I thought, oh my goodness, chemistry on a planet instead of in a test tube! I want to do that!

What prompted you to write this book?
After doing a lot of work on the ozone hole, we are constantly asked, “If we could do that [solve the problem] for ozone, can we do that for climate change?” I had a lot of experience with the Montreal Protocol policy community [an international treaty to protect the ozone layer], but also at the IPCC, which taught me a lot about how policy is made. And I was fascinated by the question: why are these problems different?

Related: How to stop the climate crisis: six lessons from the campaign that saved the ozone layer

What is the ozone layer and what does it do?
We would not have life on the Earth’s surface if we did not have the ozone layer, because it protects us from ultraviolet light from the sun, which would otherwise be very harmful to everything biological.

But in the 1980s it became clear that we were depleting this substance through, among other things, the use of chlorofluorocarbons (CFCs) in aerosol cans and refrigerators. We have many measurements showing that we have increased the amount of chlorine in the Earth’s atmosphere by about a factor of six compared to the small amount that nature can produce. So it’s mostly man-made chlorine and almost all of it comes from CFCs; hairspray and armpit deodorant were the source of the most emissions in the world.

What is the value of your child not developing asthma? How can we put a price on that?

Despite the global scale of the problem, the ozone crisis was tackled remarkably quickly.
The level of existing infrastructure investment that the chemical industry had at the time was relatively small compared to what the fossil fuel industry has today. It was always just a dozen companies worldwide and a few billion dollars at most. And the companies weren’t really forced out of the business; they were forced to change their businesses, and they showed varying degrees of recalcitrance. What I like to say to my students is: don’t think that the industry is going to do the right thing just because it’s the right thing to do; that’s not their job. Their job is to make money and your job is to hold them accountable. That is why the actions of the public and consumers are so important. In the 1970s, the mere possibility of ozone depletion led many people in the US to ditch the aerosol sprays and use forearm rollers instead. That major phase-out of voluntary consumer action had a huge effect on the market.

Besides the ozone crisis, what have you learned from researching other issues like smog and lead that we can take into the fight against climate change? global warming?
Over the years in America and Britain we have developed this anti-regulation mentality: regulation is bad, the market will find the best possible solution. Well, the market can find the most cost-effective solution. And the cost is the most important thing there, and whether that’s best or not depends on your values, because if the market finds a solution that eliminates nature, some people would worry about that. And what is actually the value of nature? And what is the value of your child not developing asthma? How can we put a price on that? We don’t put a price on those, because they depend on our values. This whole idea of, we’ll do it the cheapest way possible and we won’t pay attention to your values ​​– we’ve just got to get over that.

The industry will continue to fight, precisely because they have a lot to protect. They have huge investments in fossil fuel infrastructure. And they have all these assets, whether it’s the rights to tear down this mountaintop and sell it for coal, or offshore oil rigs, which are very expensive pieces of equipment. So when you put it all together, you end up with something on the order of a $40 trillion industry, which completely dwarfs the chemical industry at the time of the CFC issue. But it’s interesting that the concept of stranded assets has become part of the vocabulary, and people are starting to realize how much power they actually have, in terms of how we make our investments – in your pension fund or your choice of bank. And so social choice becomes part of the way people think about putting pressure on industries that are part of these assets. So this is all part of why I’m optimistic.

Related: How did we save the ozone layer?

In the Guardian last month, 380 climate scientists were surveyed and many reported feeling desperate – 77% of respondents think that global temperatures will at least increase 2.5 degrees Celsius above pre-industrial levels and 42% think they will exceed this 3C. Do you share their pessimism?
Well, the past calendar year has been a surprise – hotter than anyone expected it could or should be. A lot of work is being done to figure this out. So yes, that’s certainly scary, but I don’t share the pessimism. And frankly, I worry that climate scientists are being encouraged to take a particular position. You can see it going both ways, but in this case there has long been a group of people who believe that we should tell the worst stories possible because then the public will understand and wake up and that will enable change. That practice hasn’t really worked. You also can’t go to the [falling] price of solar energy and batteries and don’t see any major change coming. And the idea that we’re going to go beyond 3C is very difficult for me to understand, because it’s quite clear that the Paris Agreement has already put us on a trajectory that will not exceed that. Can we stay within 2 degrees Celsius, given the decline in clean energy prices? Personally, I think we can.

One lesson from your book is that, if you are an ordinary person concerned about the climate crisis, the most impactful thing you can do is work with others to create change.
Yes, that is certainly the biggest impact. It has been the kickstarter of so many past environmental problems and it has already kickstarted us on this one as well. For heaven’s sake, let’s not give up now, we are on the cusp of success. That is the fundamental message of the book.

To get back to where we started with the ozone layer. Is there still a problem up there? Is it resolved now?
We have seen chlorofluorocarbons go up, up, up and now down, down, down. So that was spectacular, a huge environmental success story. And it concerns every country in the world; the Montreal Protocol is the only UN agreement signed by every country that was formally part of the UN. That’s pretty cool.

By the way, it also helped the problem of climate change, because chlorofluorocarbons are very strong greenhouse gases. If we had not compromised on that, we would have seen an additional degree of warming by 2050, and 2 degrees Celsius would certainly have been out of reach. But we have taken it down a notch by reducing the use of chlorofluorocarbons. How cool is that?

  • Soluble: How We Healed the Earth and How We Can Do It Again by Susan Solomon is published by the University of Chicago Press (£21). In support of the Guardian And Observer Order your copy at Guardianbookshop.com. Delivery charges may apply

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