OEWG, Bangkok, Thailand22 April 2015

The information contained in this report largely derives from the Scientific Assessment of Ozone Depletion: 2014

From CFCs to HCFCs to HFCs

Co-Chairs:

Ayité-Lô AjavonPaul A. NewmanJohn PyleA.R. Ravishankara

Scientific Steering Committee:Co-Chairs &David KarolyMalcolm KoTheodore ShepherdSusan Solomon

Coordinating Editor:Christine Ennis

Ozone-depleting substances (ODSs) are decreasing

312 ppt (9%) decline of chlorine

Ozone-depleting substances (ODSs) are decreasing

2 ppt (12%) decline of Br

In spite of lifetime and bank changes from 2011, the WMO (2015) scenario is about the same

Stopping all future production of HCFCs has only a limited effect on the 2015 scenario

Destruction of all ODS banks by 2020 also has limited impact on the evolution of ODSs

Stopping all future emissions advances ODS recovery by about 11 years

CFCs emissions continue to decline, but other compounds are increasing

Let’s zoom in

In 2013, the emissions of CFCs, HCFCs, and HFCs were about equal in G tonnes CO2-equivalent

HFCs are increasing in the atmosphere

HFC-23 global abundance is growing, and emissions continue to increase

ODS contributions to climate forcing were large, but are declining as ODS levels decrease

HFC contributions are growing because of the MP, and will eventually offset the climate gains achieved by the regulation of ODSs

The combined radiative impact of CFCs, HCFCs, and HFCs will continue to grow over the next few decades

By mid-century, HFCs are beginning to dominate the total radiative forcing

By mid-century, HFCs are beginning to dominate the total radiative forcing

Summary

• ODSs are declining in our atmosphere• The radiative forcing by CFCs and

HCFCs will decline over the course of

the 21st century• Radiative forcing by future HFC

emissions can be ~25% of that of CO2

future emissions.• Future HFC emissions may hinder the

450 ppm CO2 stabilization target.