Susan Solomon Wins Tang Prize for Solving Ozone Hole Mystery, Enchanted by 'Chemistry on a Planet' [Exclusive Interview]

(CNA reporter Lin Hong-han, Cambridge, Massachusetts, June 15) — Susan Solomon, an atmospheric chemist with a background in chemistry, unraveled the mystery of the Antarctic ozone hole, producing a landmark study in environmental science. In an interview with CNA, she reflected that what fascinated her at the time was not 'chemistry in a test tube, but chemistry on a planet.'

Now 70 years old and a professor at the Massachusetts Institute of Technology (MIT), Susan Solomon is the recipient of the 2026 7th Tang Prize for Sustainable Development. Her research spans the Antarctic ozone hole, international environmental agreements, climate change assessments, and the long-term impacts of carbon dioxide, making her one of the most influential atmospheric chemists and climate scientists of our time.

Solomon authored the book 'Solvable: How We Healed the Earth, and How We Can Do It Again,' which reviews how humanity overcame environmental crises such as the ozone hole, acid rain, and smog. The title reflects her attitude toward climate issues: the problems are serious, but not unsolvable.

In her interview with CNA, she said she never thought of her work as 'saving the Earth.' As a scientist, she simply wanted to bring reliable facts into public discourse.

In 1985, British scientists published research showing a dramatic decline in ozone concentration over Antarctica. While the scientific community already knew that chlorofluorocarbons (CFCs) damaged the ozone layer, they could not explain why the depletion was particularly severe over Antarctica.

In 1986, Solomon proposed an explanation. She recalled that the key to the Antarctic ozone hole lay in unique high-altitude clouds; chemical substances that destroy ozone become activated on the surface of cloud particles, and when sunlight returns to Antarctica in spring, the ozone layer rapidly depletes.

This explanation, centered on 'heterogeneous chemistry,' later became a foundational pillar of ozone hole research.

Solomon said she was young at the time and her mind had not been 'brainwashed' by existing ideas. Many leading scientists believed surface reactions in the upper atmosphere were not significant, but existing theories could not explain the scale of the Antarctic ozone hole, so she thought in a different direction.

The ozone hole research also showed Solomon how science enters international decision-making. The 1987 Montreal Protocol, which required countries to phase out ozone-depleting chemicals, later became a rare success story in global environmental governance.

Reflecting on this experience, she learned that scientists must cross borders, integrating observations, models, and judgments from different countries to form a consensus strong enough to support policy.

Since 1986, Solomon has participated in every international scientific assessment on the ozone layer, never missing one. She told CNA she will travel to Switzerland this summer for the next round of assessments. 'I might be the last person to have attended every single one from the beginning,' she said.

Solomon later applied this experience to climate change research. From 2002 to 2008, she co-chaired Working Group I of the Intergovernmental Panel on Climate Change (IPCC), contributing to the completion of the Fourth Assessment Report.

She recalled that at the IPCC, scientists faced government representatives directly, repeatedly answering questions about the strength of evidence and the soundness of judgments.

She said scientists must distill complex research into clear, verifiable, and policy-relevant facts. How much risk society is willing to bear is a value judgment; but the actual magnitude of the risk is something science can answer. The scientist's responsibility is not to make decisions for governments or society, but to clearly communicate the facts.

The widely cited phrase from the IPCC Fourth Assessment Report, 'Warming is unequivocal,' was also Solomon's idea. She said the statement had to be both scientifically cautious and sufficiently clear, and it later became a key phrase in global climate discussions.

Another major finding by Solomon is that the warming effects of carbon dioxide emissions are long-lasting. She noted that if smog emissions stop, air quality may improve within days; but carbon dioxide is different—some of its effects persist in the atmosphere and oceans for hundreds or even thousands of years.

This makes climate change not just an environmental issue for the present generation, but also a matter of intergenerational equity. Solomon asked, 'Is it fair to leave a problem that is currently difficult to fix to future generations?'

Nevertheless, Solomon does not believe environmental issues only bring pessimism. She said humanity has already addressed the ozone hole through science, public trust, and policy cooperation—a reminder that major environmental crises are not unsolvable.

She said we cannot turn back the clock, but we can stop making the problem worse. Every additional 0.1 degree Celsius of warming could be a burden lasting centuries into the future. For her, sustainable development means not passing on risks we can reduce today to future generations. (Edited by Tang Pei-chun) 1150615