Montreal Protocol's impact on the ozone layer and climate

It is now recognized and confirmed that the ozone layer shields the biosphere from dangerous solar UV radiation and is also important for the global atmosphere and climate. The observed massive ozone depletion forced the introduction of limitations on the production of halogen-containing ozone-depleting substances (hODS) by the Montreal Protocol and its Amendments and adjustments (MPA). Further research was aimed at analyzing the role played by the Montreal Protocol to increase public awareness of its necessity. In this study, we evaluate the benefits of the Montreal Protocol on climate and ozone evolution using the Earth system model (ESM) SOCOLv4.0 which includes dynamic ocean, sea ice, interactive ozone, and stratospheric aerosol modules. Here, we analyze the results of the numerical experiments performed with and without limitations on the ozone-depleting substances emissions. In the experiments, we have used CMIP6 SSP2-4.5 and SSP5-8.5 scenarios for future forcing behavior. We confirm previous results regarding catastrophic ozone layer depletion in the case without MPA limitations. The climate effects of MPA consist of additional global mean warming by up to 2.5 K in 2100 caused by the direct radiative effect of the hODS. We also obtained dramatic changes in several essential climate variables such as regional surface air temperature, sea-ice cover, and precipitation fields. The warming rate without the MPA under the SSP2-4.5 scenario is comparable to the warming rate of the SSP5-8.5 scenario with MPA. Our research updates and complements previous modeling studies on the quantifying of MPA benefits for the terrestrial atmosphere and climate.