The Montreal Protocol at 20: Ongoing opportunities for integration with climate protection

The Montreal Protocol, implemented because of the risks posed by stratospheric ozone depletion, has successfully brought about international cooperation to address a serious global environmental hazard. We show how flexibility in destruction offsets could improve efficiency and propose a simple methodology to jointly account for the ozone and climate protection impacts of investment projects. Our approach utilizes data from projects funded by the Montreal Protocol's Multilateral Fund and from the emerging carbon emissions markets to measure what is currently being spent by governments, firms, and international agencies to reduce emissions of ozone-depleting substances and greenhouse gases. The tradeoffs and/or joint benefits implied by these expenditures can be used to evaluate future investments that reduce one or both kinds of emissions, and as a benchmark for subsequent increases in regulatory stringency. Simultaneously considering the effects of projects or technologies on the ozone layer and climate would improve progress towards achieving global environmental goals. The case of two competing refrigerants for building chillers illustrates the tradeoffs between climate and ozone impacts, and demonstrates that use of an ozone-depleting refrigerant as part of a more energy-efficient technology can be justified, particularly if the ozone-depleting compound's emissions are offset by destruction of ozone depleters that would otherwise be emitted.