Global and Regional Emissions Estimates of Non-CO2 Greenhouse gases and Ozone Depleting Substances

The Montreal Protocol is widely regarded as the most successful international environmental treaty of all time, with substantial benefits to the stratospheric ozone layer and climate.

However, recent work has shown that continued vigilance is needed following the first major violation of the Montreal Protocol, originating, at least in part, from eastern China. Since publication, Chinese authorities have reported major enforcement activities to address the problem.

However, the work highlighted several remaining scientific challenges that must be addressed to continue to support the Montreal Protocol and, for climate, the Paris Agreement.

Firstly, the magnitude of change in global emissions could not be reconciled with that inferred from eastern Asia, suggesting that the models could not accurately simulate year-to-year atmospheric trends, that the uncertainty estimates are insufficient, that as-yet-unidentified emissions occurred elsewhere in the world, or some combination of each.

Secondly, the work highlighted the critical need to develop robust global and regional emissions inference capability for the more than 40 greenhouse gases and ozone depleting substances regulated under the Montreal Protocol and other agreements.

This project will work collaboratively between the two major global monitoring networks of non-CO2 greenhouse gases and ozone depleting substances – NOAA in the USA and the international AGAGE consortium – to develop new models and statistical methodology to better quantify emissions of non-CO2 greenhouse gases and ozone depleting substances using atmospheric measurements and models of atmospheric transport, and to improve the accuracy of national and international emissions reporting.