Non-use of the Atmosphere and the Success Story of the Montreal Protocol

The atmosphere supplies goods and services that are vital for the survival and well-being of life on Earth. At the global level, two main regimes are relevant to its protection: one focuses on the ozone layer and the other addresses climate change. The ozone protection regime is based on non-use measures and is generally hailed as one of the main successes of international environmental law. This chapter examines the factors that have led, initially, to its successful adoption and, over time, to its impressive effectiveness. The chapter then turns to the climate change regime; in its current form, it is characterized by a collective non-use target and its track record is mitigated. The contrast in these two regimes’ effectiveness is striking, particularly as they originally shared many characteristics. Their divergent paths can partly be explained by design differences related to regime adaptability and by the scopes of issues to be addressed; carbon ubiquitousness and overall complexity of climate change-related processes led to negative attitudes from certain key States. This chapter concludes by highlighting some characteristics of non-use targets that could support a better outcome in the climate change regime, while also acknowledging the limited likelihood of their adoption.