In the 1980s, the world faced a huge problem: a rapidly expanding hole in the ozone layer. It was caused by widely used chemicals called chlorofluorocarbons (CFCs), which were developed in the 1920s by three US-based corporations as coolants for refrigerators. Mario Molina and Sherwood Rowland demonstrated that in the stratosphere, CFCs are broken apart by UV light, releasing chlorine atoms which react with ozone, destroying it faster than it can be replenished. Despite initial pushback from CFC producers, NASA released visualizations of the ozone depletion, which were broadcast around the world and captured public attention. In 1987, representatives of various countries signed the Montreal Protocol, requiring the rapid phasing out of CFCs and creating a fund to assist Global South countries in obtaining affordable, non-ozone depleting alternatives. In 1995, Molina, Rowland, and their Dutch colleague Paul Crutzen were jointly awarded the Nobel Prize in Chemistry. The ozone hole is predicted to disappear entirely by 2070, but we’re not out of the woods yet. The alternatives that replaced CFCs— hydrofluorocarbons (HFCs)— are potent greenhouse gases and are contributing to climate change. In 2016, the Kigali Amendment was added to the Montreal Protocol, which calls for an 85% cut in global HFCs by 2047. This could potentially avoid up to 0.5°C of global warming by the end of the century. The Montreal Protocol serves as an example of the decisive global cooperation required to combat climate change. The question is, what will it take for us to come together again?