Ozone Depletion by Hydrofluorocarbons

Transcription

1 Ozone Depletion by Hydrofluorocarbons Margaret M. Hurwitz 1, 2, Eric. L. Fleming 2, 3, Paul A. Newman 2, Feng Li 2, 4, Eli Mlawer 5, Karen Cady-Pereira 5, and Roshelle Bailey 1, 2 1 GESTAR, Morgan State University, USA 2 NASA Goddard Space Flight Center, USA 3 Science Systems and Applications, Inc., USA 4 GESTAR, Universities Space Research Association, USA 5 Atmospheric and Environmental Research, USA

2 HFCs effects simulated with an atmospheric model Surface mixing ratio (ppbv) Emissions follow high scenario (Velders et al., 2009) & business-as-usual scenario (Miller and Kuijpers, 2011) simulations with an atmospheric chemistry-climate model (NASA GSFC 2D model, Fleming et al., 2011) Includes effects of HFCs on atmospheric temperature, circulation and stratospheric chemistry

3 Quantifying the Impacts of HFCs on Climate and Stratospheric Ozone PI: Maggie Hurwitz Co-Is: Eric Fleming, Feng Li & Paul Newman Funding: NASA ACMAP HFCs cause a weak, net ozone depletion as atmospheric concentrations increase and stratospheric temperature increases

4 Temperature and circulation changes affect ozone Hydrofluorocarbons (HFCs) are strong radiative forcers with rapidly increasing atmospheric concentrations ozone decrease ozone increase

5 HFCs warm the troposphere and stratosphere Hydrofluorocarbons (HFCs) are strong radiative forcers with rapidly increasing atmospheric concentrations Peak warming of ~0.4K at 72hPa

6 Atmospheric Absorption (%) Earth s surface and atmosphere emit IR radiation Photos escape to space Wavelength (mm) Photos absorbed before they reach space

7 Atmospheric Absorption (%) Atmospheric gases absorb IR radiation Wavelength (mm) CO H O3 2 2 O

8 Atmospheric Absorption (%) HFCs absorb radiation in the atmospheric window Wavelength (mm) Illustration of the future HFC contribution

9 HFC enhance the stratospheric circulation

10 Temperature and circulation changes affect ozone Due to warming and enhanced upwelling Hydrofluorocarbons (HFCs) are strong radiative forcers with rapidly increasing atmospheric concentrations Less polar ozone loss Due to circulation changes

11 PREVIOUS STUDIES Change in global total column ozone per unit mass emission of HFC-X Chemistry contribution Ozone Depletion Potential (ODP) for HFC-X = Change in global total column ozone per unit mass emission of CFC-11 Chemistry contribution Temperature contribution Circulation contribution

12 THIS STUDY Change in global total column ozone per unit mass emission of HFC-X Chemistry contribution Temperature contribution Ozone Depletion Potential (ODP) for HFC-X = Circulation contribution Change in global total column ozone per unit mass emission of CFC-11 Chemistry contribution Temperature contribution Circulation contribution

13 ODPs from previous studies HFC-32 HFC-134a HFC-125 HFC-143a HFC x x x 10-5 * * * HCFC-22 CFC x ^ * Ravishankara et al. (1994) ^ WMO (2014)

14 ODPs based on ATMOSPHERIC SIMULATIONS HFC ± 0.18 x 10-3 HFC-134a 1.3 ± 0.4 x 10-3 HFC ± 0.5 x 10-3 HFC-143a 4.2 ±1.4 x 10-3 HFC ± 6 x 10-3 ODPs from previous studies 1.5 x x x 10-5 HCFC x 10-3 CFC x

15 Quantifying the Impacts of HFCs on Climate and Stratospheric Ozone PI: Maggie Hurwitz Co-Is: Eric Fleming, Feng Li & Paul Newman Funding: NASA ACMAP HFCs cause a weak, net ozone depletion as atmospheric concentrations increase and stratospheric temperature increases

16 Ozone depletion proportional to HFC emissions

17 Ozone depletion proportional to HFC emissions

18 3 3 Ozone depletion proportional to HFC emissions Controlled by HFC emissions Controlled by physics of HFC molecules

19 Ozone depletion proportional to HFC emissions More ozone depletion Current projections Less ozone depletion Large HFC concentrations in 2050 X HFCs with large radiative efficiencies

20 Ozone depletion proportional to HFC emissions More ozone depletion Lower HFC concentrations Less ozone depletion Lower HFC concentrations in 2050 X HFCs with large radiative efficiencies

21 Ozone depletion proportional to HFC emissions More ozone depletion Less ozone depletion Low HFC concentrations & HFCs with small radiative efficiencies Lower HFC concentrations in 2050 X HFCs with smaller radiative efficiencies

22 Simulated Ozone Depletion (DU) Ozone depletion proportional to HFC emissions 0.08 More ozone depletion Less ozone depletion HFC-32 HFC-23 HFC-134a HFC-143a Gases with very low concentrations and/or small GWPs HFC Lower HFC HFCs with smaller concentrations 2050 Surface Concentration in 2050 X x Radiative radiative Efficiency efficiencies (W/m 2 )

23 Summary HFCs are weak but non-zero ozone-depleting substances Projected decrease in global total ozone of 0.035% in 2050 ODPs range from 0.39x10-3 to 30x10-3 HFC-125 projected to be the largest contributor to HFC-related ozone depletion Ozone depletion by HFCs results from a combination of stratospheric temperature and circulation changes Reducing HFC emissions, and thus their radiative forcing, would reduce the HFC impacts on the stratosphere Hurwitz, M. M., E. L. Fleming, P.A. Newman, F. Li, E. Mlawer, K. Cady-Pereira, and R. Bailey (2015). Ozone Depletion by Hydrofluorocarbons. Geophysical Research Letters, 42, doi: /2015gl