Four Decades of Ozone Layer Depletion: What We Did Right and What We Could Have Done Different? (Invited Keynote Presentation)

Molina and Rowland's seminal paper in 1974 led to the recognition of the global environmental problem of ozone layer depletion caused by anthropogenic emissions of chlorofluorocarbons. Subsequently, the list of substances that can deplete the ozone layer grew and included many chlorinated and brominated chemicals. The ozone layer depletion was evident on a global scale and dramatically in the Antarctic Spring time as the ozone hole. Faced with this global scale problem, amazingly, the nations of the world took action in adopting the Vienna Convention and subsequently the Montreal Protocol. Now, thanks to the seminal work of Molina and Rowland and the actions of the world community, the ozone layer is on the mend. Further more, the Protocol helped climate by stopping the production of the ozone depleting substances, which are also greenhouse gases.

Many things were done right in making Montreal Protocol a success. I will describe some of the features of the Montreal Protocol that enabled success. Then, we ask the question: Could something else been done using the chemicals and technologies that were already available prior to the Montreal Protocol or even subsequent to the Protocol? I will describe our work on potential pathways that could have been taken and what the ramifications of those steps would have been to the ozone layer and climate.