Abstract
The Environmental Effects Assessment Panel of the Montreal Protocol under the United Nations Environment Programme evaluates effects on the environment and human health that arise from changes in the stratospheric ozone layer and concomitant variations in ultraviolet (UV) radiation at the Earth’s surface. The current update is based on scientific advances that have accumulated since our last assessment (Photochem and Photobiol Sci 20(1):1–67, 2021). We also discuss how climate change affects stratospheric ozone depletion and ultraviolet radiation, and how stratospheric ozone depletion affects climate change. The resulting interlinking effects of stratospheric ozone depletion, UV radiation, and climate change are assessed in terms of air quality, carbon sinks, ecosystems, human health, and natural and synthetic materials. We further highlight potential impacts on the biosphere from extreme climate events that are occurring with increasing frequency as a consequence of climate change. These and other interactive effects are examined with respect to the benefits that the Montreal Protocol and its Amendments are providing to life on Earth by controlling the production of various substances that contribute to both stratospheric ozone depletion and climate change.
Highlights
Since the last 2020 EEAP Update Assessment [1], new information on the beneficial effects of the Montreal Protocol on the stratospheric ozone layer has become available and is assessed
Extended author information available on the last page of the article resulting from the 2020 Arctic low-ozone episode, and recent projections of Arctic ozone and UV radiation linked to climate change
Modelling studies suggest that summertime precipitation in the Southern Hemisphere, with some regions projected to get drier and others wetter, will be more affected by future increases in the concentration of greenhouse gases (GHG) and warming of the tropical upper troposphere than by stratospheric ozone recovery resulting from the implementation of the Montreal Protocol [7]
Summary
Solar UV radiation drives chemical transformations in the troposphere that have beneficial and harmful consequences. The reaction of OH radicals with these ODS replacement compounds (HFCs, HCFCs, HFEs and HFOs) produces trifluoroacetic acid (TFA) in the atmosphere, which is transported in precipitation to the Earth’s surface. 2.3 Atmospheric concentrations of third‐generation CFC‐replacement compounds, HFOs and HCFOs, continue to increase, but the impact on local air quality is not significant. The oxidation products of the HFOs and HCFOs are, in general, similar to those occurring from degradation of the HFCs and HCFCs, and include carbonyl compounds that have the potential to yield trifluoracetic acid (TFA), through hydrolysis or via secondary photochemistry [47]. Models indicate that a direct replacement of HFC-134a with HFO1234yf in refrigeration applications will increase the associated global TFA burden from an annual 65 to 2220 tonnes formed from an equivalent emission of HFO-1234yf (based on emissions in 2015) [48]. The paucity of data on sensitivity of marine plants to TFA is a potential source of uncertainty in the assessment of risks, especially as marine waters and endorheic lakes (lakes without an outflow) are the terminal basins for TFA, regardless of source
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