The Montreal Protocol that was signed in 1987 is widely regarded as one of the most important pieces of international cooperation on environmental issues. It created a phased ban on chlorofluorocarbons, or CFCs, the principal culprit of the so-called hole in the ozone layer, now greatly diminished, due in large part to this agreement. Just this past weekend, nearly 30 years later, representatives from 140 nations gathered in Kigali, Rwanda to amend the Montreal Protocol on Substances that Deplete the Ozone Layer. This time, the aim was to phase out the use of hydrofluorocarbons or HFCs, which don’t affect the ozone layer, but are among the most potent greenhouse gasses that humans produce. This week on Sea Change Radio, we talk with one of the key figures behind the Montreal Protocol and Kigali Amendment, international environmental lawyer and founder of the Institute for Governance and Sustainable Development, Durwood Zaelke.