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HFCs: A Critical Link in Protecting Climate and the Ozone Layer

HFCs: A Critical Link in Protecting Climate and the Ozone Layer. A. R. Ravishankara Guus Velders Melanie Miller Mario Molina. Steering committee headed by Joseph Alcamo. Disclaimer: I am not talking as a co-Chair of WMO/ENEP SAP panel

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HFCs: A Critical Link in Protecting Climate and the Ozone Layer

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  1. HFCs: A Critical Link in Protecting Climate and the Ozone Layer A. R. Ravishankara GuusVelders Melanie Miller Mario Molina Steering committee headed by Joseph Alcamo Disclaimer: I am not talking as a co-Chair of WMO/ENEP SAP panel Opinions expressed are mine and not necessarily those of NOAA

  2. Provisions of the MP led to decreases in ODS • The Montreal Protocol is working and the ODSs are declining. • HCFCs, the transition substitutes, are not contributing greatly to ozone depletion.

  3. Montreal Protocol’s role in safeguarding the ozone layer. WMO/UNEP SAP 2011 Newman et al. • MP prevented major global ozone layer depletion • Current ozone layer depletions are small, except for the polar spring time ozone depletions. • Ozone layer will recover in this century. Ozone hole will heal towards the end of this century.

  4. Montreal Protocol effectively protected climate • ODS-Phase out led to a drop of ~ 8.0 GtCO2eq per year (1988 -2010). • The avoided annual ODS emission (~ 10 Gt CO2eq in 2010 alone) • - x5 the Kyoto target for 2008-2012 (1st commitment period). • ODS decrease: one of the largest intentional global GHG emission reductions to date

  5. Montreal Protocol “led” to HFC use • MP successfully phased out CFCs and is phasing out HCFCs. • Phase out done via use of substitute chemicals or other approaches • HFCs are the main replacements in many ODS applications

  6. Use of HFCs is increasing • Consumption of HFCs is increasing rapidly • Consequent atmospheric growth rate of some HFCs are increasing very rapidly (some as much as 10% per year) • The current contributions of HFCs to radiative forcing is still small (<1% of GHGs)

  7. Climate benefits of Montreal Protocol may be lost because of growth in HFCs • Unabated, future HFC emissions may offset climate benefit of MP. • HFC emissions expected could be ~3.5 to 8.8 GtCO2eq in 2050. • Roughly equivalent to: • - ODS annual emissions drop of 8.0 GtCO2eq per year for 1988 -2010 • - 7 to 19% of the CO2 emissions in 2050 (SRES) • - 18 to 45% of CO2emissions for the 450 ppm CO2. • There is, of course, inherent uncertainty in such projections.

  8. HFCs contribution to climate change by future emissions can be large • Unabated, future HFC contribution radiative forcing can be large. • Radiative forcing by future HFC emissions can be ~25% of that of CO2 future emissions (SRES scenarios). • Future HFC emissions can significantly hinder the 450 ppm stabilization target.

  9. Low GWP-HFCs can retain climate benefits of MP. • Currently HFC contrbute <1% of the total radiative forcing. • HFCs are not all the same! Many HFCs (with shorter lifetimes) have very low GWPs. • There do not appear to be other major environmental problems with the use of very low GWP HFCs. • Possible to retain a <1% contribution in 2050 using low-GWP HFCs (GWP <20) and other alternatives, even for the upper range emissions Scenarios.

  10. Summary • MP effectively protected climate. • HFCs were introduced mostly because of MP • Currently HFCs are not significant for climate forcing • Future climate forcing by HFCs can be very large because of using high-GWP HFCs • There are many ways to reduce the climate influence of high-GWP HFCs Thank you for your attention & Over to Dr. Melanie Miller

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