When Mario Molina won the Nobel Prize in 1995 for his research on CFCs, the award came with a new responsibility: To communicate science and influence policy.
In the mid-1970s, he and a colleague figured out that chemicals called chlorofluorocarbons remained in the atmosphere after being used in things like aerosol cans. Remaining CFCs could lead to ozone depletion.
So they warned policymakers about the dangers of the chemicals.
"We decided it was our job to make sure that society would learn about this issue," he said.
Society learned about the problem — and solved it — with an international agreement to ban all CFCs that prevented a hole in the ozone from getting worse.
And now Molina's tackling a new behemoth: Climate change, and how to talk about it.
He's bringing that mission to the Twin Cities this week, along with 2009 laureate Elizabeth Blackburn and 2004 laureate David Gross in a two-day symposium sponsored by 3M and Nobel Media.
At an event Wednesday, hundreds of scientists and students gathered at 3M's headquarters to hear him speak about his work urging international policymakers toward a global agreement on climate change. He was there to witness the culmination of that work, when the Paris climate agreement was signed in 2015.
It's been a challenge, Molina told the crowd: Efforts to address climate change are far more politicized than his earlier work educating people about CFCs.
Fossil fuel companies and others have worked to cast doubt about climate science, he said. They've zeroed in on small elements of uncertainty in the complex science of climate change. Molina described their conclusions about it as a house of cards.
"So if you find one problem, [you] remove a card, [and] it falls apart," he said. "That's not the way science works, and that's not the way climate change works."
Instead, Molina used a different metaphor. The science of climate change, he said, is more like a puzzle.
He projected a picture of a puzzle onto a screen behind him. It was missing a few pieces, but despite that was very clearly a picture of a tiger.
"You can more or less see what's behind that — and it's not a very nice little kitten, OK?"
Sitting in the audience Wednesday was a group of students from Macalester College.
Biology major Jaclyn Kline said Molina's approach to talking about science — with the stories and the metaphors and the visual language — has inspired her to think more about the ways she does the same.
"It was useful to see that take on how to do scientific storytelling to achieve a goal," she said.
And explaining climate science in an accessible way is becoming increasingly crucial. The climate is clearly changing, and it's happening now. The question, Molina said, is this: How bad will it get in the future?
To avoid a climate catastrophe, he said, humans need to increase their efforts to phase out fossil fuels — and, with a little innovation, those efforts might just also be good for the economy.
"If you are sufficiently creative," he said, "you can end up winning."
Molina will speak to hundreds of more students and researchers on Thursday at the University of Minnesota and the Science Museum of Minnesota.