Speaker
Dr
Paul Newman
(NASA Goddard Space Flight Center)
Description
The Montreal Protocol on Substances that Deplete the Ozone Layer mandates a quadrennial report from their Scientific Assessment Panel under Article 6 of the agreement. The most recent assessment was the “Scientific Assessment of Ozone Depletion 2022” (https://ozone.unep.org/system/files/documents/Scientific-Assessment-of-Ozone-Depletion-2022.pdf). The potential areas of focus for the 2026 report were formulated at the 35th Meeting of the Parties in Nairobi, Kenya in October 2023 under Decision XXXV/3. In this talk, I will cover some of the main findings of the 2022 Assessment and briefly discuss the areas of focus for the 2026 report.
Decision XXXV/3 areas of focus specifically included:
- An assessment of the state of the ozone layer and its future evolution;
- An evaluation of global and polar stratospheric ozone, including the Antarctic ozone hole and Arctic winter and spring ozone depletion and the predicted changes in these phenomena;
- An updated assessment of past and projected contributions of the Montreal Protocol to mitigating climate change in terms of total avoided CO2-equivalent emissions and avoided temperature increase;
- An evaluation of trends in the top-down derived emissions, abundances and fate in the atmosphere of trace gases of relevance to the Montreal Protocol, in particular controlled substances and other substances of importance to the ozone layer, which should include a comparison of top-down estimations and available bottom-up estimations of such emissions with a view to identifying currently unknown emission sources and explaining discrepancies between emissions derived from reported information and observed atmospheric concentrations (in cooperation with the Technology and Economic Assessment Panel);
- An evaluation of consistency with reported production and consumption of those substances and the likely implications for the state of the ozone layer, including its interaction with the climate system;
- An assessment of the interaction between changes in stratospheric ozone and the climate system, including consideration of related policy scenarios;
- Information regarding scenarios designed to contribute further to ozone layer protection and climate change mitigation, and a presentation of their benefits in terms of impacts on total column ozone and equivalent effective stratospheric chlorine, advancing the recovery of the ozone layer, and avoiding CO2-equivalent emissions, as relevant;
- Early identification and quantification of any substances that could be of concern for the ozone layer and relevant for the implementation of the Montreal Protocol and the objectives of the Vienna Convention for the Protection of the Ozone Layer, including other halogenated gases, in particular those with high global warming potential, breakdown products of controlled substances and their alternatives that are very persistent, such as perfluoro- and polyfluoroalkyl substances, including trifluoroacetic acid, N2O and very short-lived substances such as dichloromethane, and their main sources of emissions;
- An assessment of information and research related to solar radiation modification, in particular stratospheric aerosol injection and its potential effects on the ozone layer and relevant information on the potential effects of supersonic aircraft, rockets, satellites, wildfires and volcanic eruptions on the stratospheric ozone layer;
- Identification and quantification of any other issues relevant to the objectives of the Vienna Convention for the Protection of the Ozone Layer and the Montreal Protocol.
Primary author
Dr
Paul Newman
(NASA Goddard Space Flight Center)
