Intercontinental scale transport of air pollution

1. Intercontinental scale transport of air pollution John Murlis Department of Geography University College London Based on a presentation by Henning Rodhe Stockholm University

2. Overview • Pollution acts on a wide range of scales • Impacts vary across scales • Management regimes developed, but gaps remain • Evidence for impacts on different scales: • Acidification/Eutrophication • Ozone • Aerosols/Particulate matter • Conclusions

3. Pollution Acts on a Range of Scales • Local • Regional • Intercontinental/Hemispheric • Global

4. The Great London Smog Disaster, 1952

5. Regional scale pollutants • Lifetime days to weeks • Components related to • - Acidification (SOx, NOx, NHx) • Eutrophication (NOx, NHx) and • Aerosol formation (SOx, NOx, • NHx, Carbon compounds) • Particulate matter

6. Regional air pollutionWhat are the issues? • Acidification: soil chemistry, lake ecology (SOx, NOx, NHx) • Eutrophication: algal blooms, biodiversity (NOx, NHx) • Excess ozone: health, vegetation, climate (NOx, VOC, CO) • Aerosols: health, climate (SOx, NOx, NHx, VOC,..) • Corrosion (SOx, H+, O3, NOx, ) • Toxic species (Hg, Pb, Cs-137, PCB …)

7. Continental and hemispheric scale pollutants Life time weeks to months Tropospheric ozone and its precursors (NOx, VOC, CO..) Particulate Matter?

8. Daniel Jacob, 2002

9. North America CO over Germany Huntzinger & Schlager 2004

10. Origins of model ozone at Mace Head, Ireland Model calculations by Derwent et al. 2002

11. Global scale pollutants Lifetime > years * Longlived greenhouse gases and ozone depleting substances: CO2, CH4, N2O, CFCs,.. * Stratospheric aerosols * Mercury

12. Evolution of the perceived spatial scale of air pollution problems in the US Keating et al., 2004

13. Regional/Hemispheric Scale • Acidification and Eutrophication • Sulphur and Nitrogen

14. Soil sensitivity to acid deposition Kuylenstierna et al. Ambio 2001

16. Simplified model of precipitation acidity: [H+]= [SO42-]+ [NO3-]- [NH4+]- [Ca2+] When [H+]> 0: ‘real’ [H+] When [H+]< 0: [HCO3-]

17. Number of years to deplete base cations in soil NE India 150 (40 – 220) Malaysia 110 (40 – 160) S China 17 (6 – 35) Hicks et al. 2004

18. Sulfur

19. European sources North American sources Continental scale transport of man-made sulfur Tarrason & Iversen, 1998

20. Sulfur deposition Magnuz Engardt SMHI Sweden Pers. com.

21. Estimates of S deposition Emissions only from Andra Pradesh, Kamataka, Goa Oxidizedsulfur MATCH model calculations (RAPIDC) by Magnuz Engardt, SMHI, Sweden

22. Nitrogen

23. Estimates of S and N deposition Emissions only from Andra Pradesh, Kamataka, Goa Oxidizedsulfur Oxidized nitrogen MATCH model calculations (RAPIDC) by Magnuz Engardt, SMHI, Sweden

24. S and N Future Emissions?

25. Global SO2 emission scenarios (SRES) Tg S/yr 180 120 60 1990 2010 2030 2050 2070 2090 Nakicenovic et al. 2000

26. IPCC Special Report on Emissions Scenarios SO2

27. Emissions of SO2 from land-based sources in the 25 EU countries and from international shipping in European sea areas 2000 2005 2010 2015 2020 2025 2030

28. IPCC Special Report on Emissions Scenarios NOx

29. S Asia E Asia FSU China Europe N America

30. Conclusions on S and N (Acidification and Eutrophication Intercontinental transport does occur but how significant is it? UNECE Task force will assess for N Northern Hemisphere

31. Ozone

32. Contributions to ozone over Japan from Europe, US, East Asia and Japan Total European N American E Asian From Wild et al. JGR June 2004 Local

33. Estimate of a possible increase in surface ozone 2000 to 2100 Prather et al. GRL 2003

34. Keating et al. 2004

35. Conclusions on ozone *Potential for large increase of ozone levels in many tropical and subtropical countries (China, India, Africa) as NOx emissions go up * Ozone and its precursors (CO, VOC, NOx) subject to substantial intercontinental transport * N H background of ozone may reach standard values set for health during this century

36. Aerosols

38. Pollution haze over NE India and the Bay of Bengal December 2004

39. Brown haze over Nepal, UNEP ABC Assessment report 2002

40. Aerosol optical depth over China August 2004 MODIS satellite data

41. Model - JJA Extinction of sunlight due to aerosols in China Fig. 5. Simulated (top) and obs Observations - JJA Qian et al. Tellus B 2003

42. S of ITCZ N of ITCZ Total Aerosol components in surface air during ABC NSS-sulfate Ammonium Potassium Calcium Sea salt Norman et al. 2003

43. Trans-Pacific transport path of Asian dust to North America in April 1998

44. Cloud forcing due to sulfate aerosols Temperature response Ekman & Rodhe, 2003

45. Conclusions on aerosols Intercontinental scale transport does occur (episodically) but how significant as a driver of control strategy ?

46. A subjective expert ”concern list” of air pollution issues at different scales: • Aerosols and health: urban & regional • 2. Aerosols and climate: global (interactions • with radiation and with clouds) • 3. Tropospheric ozone: regional/hemispheric • (agriculture, health) • 3. N, S: regional/hemispheric (Acidification/ • eutrophication)

47. Prospects for the future - Sulfuremissions: up in China, India .. down in Europe, US .. global total up - or down - NOx: up in many developing countries - NH3:? - Ca: probably down

48. Conclusions • Transport on a Regional/Hemispheric Scale established for wide range of air pollutants • Further work needed to establish full significance • At this stage, most concern about tropospheric ozone • Some concern about pm/aerosol • N and S Significant but regional transport still dominates • As local and regional pollution comes under control, longer range transport will be more significant