Overview of current and projected atmospheric HFC abundances A.R. Ravishankara On behalf of co-Chairs of SAP Ayité-Lo Ajavon Paul Newman John Pyle A.R. Ravishankara 4/20/15HFC Workshop, Bangkok1

Evolution of strategy to eliminate ozone depleting substances  MP successfully phased out CFCs and is phasing out HCFCs.  Phase out done via use of substitute chemicals or other approaches. CFCs, Halons, CH 3 Br, CCl 4, MCF, etc. CFCs, Halons, CH 3 Br, CCl 4, MCF, etc. HCFCs High GWP HFCs Low GWP HFCs Alternate technologies Burkholder, Cox, and Ravishankara, /20/15HFC Workshop, Bangkok2

HFCs are the outgrowth of the ODS- substitution strategy  HFCs are the main replacements in many ODS applications.  HFCs growth is primarily due to their uses as ODS- substitutes.  HFC productions are increasing rapidly. Some HFCs are potent greenhouse gases. e.g., HCFC-134a- GWP~1300 (compare with CFC-12 with GWP ~10,000) 4/20/15HFC Workshop, Bangkok3 UNEP HFC report

Atmospheric observations show increases in HFCs  All HFCs are increasing. Most HFCs are increasing rapidly…  Current HFC abundances are still small – together their abundance is roughly < 115 ppt (excluding HFC-23), i.e., 20% of the current CFC-12 abundance. 4/20/15HFC Workshop, Bangkok4 WMO/UNEP 2014 SAP report

Emissions of HFCs are increasing 4/20/15HFC Workshop, Bangkok5  Atmospheric observations show that HFC emissions are increasing.  Recent HFC-23 emission changes are consistent with effectiveness of the Clean Development Mechanism (CDM) in recapture and destruction. Total HFC-23 HFCs used as ODS substitutes Using data from WMO/UNEP 2014 SAP report

Uses of HFCs (ODS substitutes) 4/20/15HFC Workshop, Bangkok6  MAC, refrigeration, and other uses are roughly the same.  Emissions from all uses are increasing at roughly the same rate. From Montzka et al. 2014/2015

Increases are consistent with estimates 4/20/15HFC Workshop, Bangkok7 Emissions from countries not reporting to UNFCCC  Emissions from countries not expected to report to UNFCCC are increasing very rapidly.  Emissions are consistent with Velders et al estimates for total and individual chemicals…. Lends confidence to projections. From Montzka et al., 2014/2015 Consistent with Velders et al Projections From Observations Reported to UNFCCC

Details of HFC emissions projections are becoming available 4/20/15HFC Workshop, Bangkok8 Velders et al., 2015 (to be published)  Emission projections for various geographical regions and usage sectors are becoming available Regional Emissions Sectoral Emissions

HFC could contribute largely to future climate change  Future HFC contribution to climate change (as measured by radiative forcing) can be large. o Radiative forcing by future HFC emissions can be ~25% of that of CO 2 future emissions. HFC Workshop, Bangkok94/20/15 CFCs and HCFCs Various HFC Scenarios WMO/UNEP 2014 SAP report

HFCs contribution to climate change by future emissions can be large  Radiative forcing by future HFC emissions can be ~25% of that of CO 2 future emissions (scenarios from SRES).  Future HFC emissions can significantly undermine achievements of the 450 ppm stabilization targets. HFC Workshop, Bangkok104/20/15 From UNEP HFC report

There are ways to avoid large climate effects of HFCs  Use low-GWP HFCs (GWP <20) and other alternatives will retain a <1% contribution in 2050 by, even for the upper range emissions scenarios.  Such alternatives appear to be available.  Impact of TFA from HFO-1234yf, a potential substitute, are considered to be negligible over the the next decade. Potential longer-term impacts require future evaluations. HFC Workshop, Bangkok114/20/15 Radiative Forcing (W m -2 ) Year Progressively lower GWP From UNEP HFC report

Thank you for your attention. 4/20/15HFC Workshop, Bangkok12

Backup slides 4/20/15HFC Workshop, Bangkok13

Detailed projections 4/20/15HFC Workshop, Bangkok14

4/20/15HFC Workshop, Bangkok15

HFCs are increasing in the atmosphere  e.g., HFC-134a used in mobile air conditioners has increased about 7% a year over the past two years.  HFC-23, a byproduct of HCFC-22 production, is also increasing.  The current contribution of HFCs to climate change is still small (<1% of GHGs). 4/20/15HFC Workshop, Bangkok16 Parts per Trillion (ppt) Emission (kiloTonnes per yr) HFC-23 Abundances Emissions

Montreal Protocol phased out CFCs!  “Unnecessary”, e.g., Propellant, usage dropped very quickly- easy step  Allowed use of existing equipment with “drop in” substitutes- by using HCFCs  Allowed a gradual switching to better substitutes  Allowed emergence of “not-in-kind” technologies and other chemicals Refrigerants Foam Expansion Solvents Propellants Fire Extinguishants Other 4/20/15HFC Workshop, Bangkok17

HFC future contribution to climate: can be large but can be avoided  Future HFC contribution to climate change (as measured by radiative forcing) can be large. o Radiative forcing by future HFC emissions can be ~25% of that of CO 2 future emissions. o Future HFC emissions can hinder the 450 ppm CO 2 stabilization target. o Replacement of current mix of high-GWP HFCs with low-GWP compounds and not-in- kind technologies would essentially avoid these climate effects of HFCs. o TFA from HFO-1234yf, a potential substitute, are considered to be negligible over the the next few decades. Potential longer-term impacts require future evaluations. HFC Workshop, Bangkok184/20/15 Various HFC Scenarios

Future HFCs contributions  Radiative forcing by future HFC emissions can be ~25% of that of future CO 2 emissions (scenarios from SRES).  Future HFC emissions can significantly hinder the 450 ppm stabilization target.  Possible to retain a <1% contribution in 2050 by using low-GWP HFCs (GWP <20) and other alternatives, even for the upper range emissions Scenarios. HFC Workshop, Bangkok 19 4/20/15 Assuming the current mix of HFCs