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By phasing out production and consumption of most ozone-depleting substances (ODSs), the Montreal Protocol on Substances that Deplete the Ozone Layer (Montreal Protocol) has avoided consequences of increased ultraviolet (UV) radiation and will restore stratospheric ozone to pre-1980 conditions by mid-century, assuming compliance with the phaseout. However, several studies have documented an unexpected increase in emissions and suggested unreported production of trichlorofluoromethane (CFC-11) and potentially other ODSs after 2012 despite production phaseouts under the Montreal Protocol. Furthermore, because most ODSs are powerful greenhouse gases (GHGs), there are significant climate protection benefits in collecting and destroying the substantial quantities of historically allowed production of chemicals under the Montreal Protocol that are contained in existing equipment and products and referred to as ODS “banks”. This technical note presents a framework for considering offsets to ozone depletion, climate forcing, and other environmental impacts arising from occurrences of unexpected emissions and unreported production of Montreal Protocol controlled substances, as recently experienced and likely to be experienced again. We also show how this methodology could be applied to the destruction of banks of controlled ODSs and GHGs or to halon or other production allowed under a Montreal Protocol Essential Use Exemption or Critical Use Exemption. Further, we roughly estimate the magnitude of offset each type of action could provide for ozone depletion, climate, and other environmental impacts that Montreal Protocol Parties agree warrant remedial action.

This paper recalls and documents the military leadership under the Montreal Protocol, presents indicative case studies of how technical performance of military systems was maintained or improved by adopting newer technologies and summarizes key lessons from military leadership in protecting the ozone layer. In addition to collaboration on technology development and demonstration, between 1991 and 2009, military organizations from various countries came together to conduct seven workshops specifically to review military ODS uses, share experiences with alternatives, and compare policy approaches to extract and share best practices. Lessons such as this can be applied to developing and adopting technologies that displace the need to emit greenhouse gas while improving the performance of military systems and reducing operating costs.

Stratospheric ozone, global warming, and the principle of unintended consequences—An ongoing science and policy success story.

Issue of Our Planet, the magazine of the United Nations Environment Programme.