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.