The Montreal Protocol has put the ozone layer on a path to recovery by phasing out 99 % of banned ozone-damaging substances. Most of these substances are also potent greenhouse gases. Atmospheric monitoring has detected unexpected increases in emissions in several of these banned substances. Here we present an approach for quantifying damage to ozone, climate and health for these emissions and offset by preventing the equivalent emissions of ozone-damaging substances.

An accurate estimate of radiative efficiency (RE) is substantial for an accurate assessment of global warming potential (GWP). In this study, we report accurate estimates of RE values of emerging greenhouse gases (GHGs) by using high-resolution Fourier transform infrared spectroscopy (FTIR). CF₃OCFCF₂ and CF₃OCF₂CF₃ are reported for the first time. In addition, hidden errors in RE values of (CF₃)₂CFCN and CF₃OCFCF₂ in previous studies are pointed out.

The thermal equilibrium constant governing the partitioning of the chlorine monoxide radical (ClO) and its dimer, chlorine peroxide (ClOOCl), was measured by broadband UV spectroscopy in the temperature range of 228–301 K. Uncertainty in the value of this equilibrium constant produces significant uncertainty in model determinations of expected polar ozone loss extent. The key results of this study indicate that the currently recommended uncertainty for this reaction may be reduced.

A lack of policy-relevant metrics for hydrochlorofluorocarbons (HCFCs) regulated in the Montreal Protocol is addressed by providing reliably estimated metrics for all HCFCs included in the protocol. This research provides reliable policy-relevant metrics (e.g., atmospheric lifetimes, ozone depletion and global warming potentials) based on well-established estimation methods. The results from this work provide the Montreal Protocol the information needed for informed policy decisions.

We have investigated for the first time the heterogeneous hydrolysis of ClONO₂ on TiO₂ and SiO₂ aerosol particles at room temperature and at different relative humidities (RHs), using an aerosol flow tube. The kinetic data reported in our current and previous studies have been included in the UKCA chemistry–climate model to assess the impact of TiO₂ injection on stratospheric chemistry and stratospheric ozone in particular.