On this World Ozone Day 2025, we are reminded that the story of the ozone treaties is one of the most inspiring examples of global cooperation, scientific foresight, and environmental stewardship. These landmark agreements demonstrated how science can alert the world to emerging threats and guide decisive action. For almost forty years, the world has been considering the science behind the impacts of human activity on the ozone layer and the resulting impacts on climate and human health.

Science, together with support from the Multilateral Fund are key to the Montreal Protocol’s success. On the one hand, science is at the core of the Protocol’s flexibility whereby it became stronger as scientific understanding evolved. Its design anticipated evolving scientific knowledge, ensuring it could adapt to new findings and emerging challenges. This has allowed the Protocol to pivot over the past thirty-five plus years, allowing for additional substances to be recognized and frameworks developed to address them.

Funding, on the other hand, is crucial to the implementation of the Montreal Protocol and its Amendments. The Multilateral Fund provides the support needed to ensure that all countries can develop the legislation, tools and technology required to meet the Protocol requirements and allows the necessary flexibility for countries to develop their own strategies and plans. From supporting the phase-out of CFCs to the phase-down of HFCs and beyond, the Fund has evolved its support to better assist Article 5 countries to meet changing implementation requirements.

Science, both analysis and actual atmospheric monitoring, continues to form the basis of all decisions relating to the Montreal Protocol and to the Multilateral Fund. This World Ozone Day reminds us all of the amazing value of science and of the scientists that have accompanied the evolution of the Montreal Protocol for the last four decades.