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 pollution What 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 +, O 3, 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. Huntzinger & Schlager 2004 North America CO over Germany

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

11. Global scale pollutants Lifetime > years * Longlived greenhouse gases and ozone depleting substances: CO 2, CH 4, N 2 O, CFCs,.. *Stratospheric aerosols *Mercury

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

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 + ] = [SO 4 2- ] + [NO 3 - ] - [NH 4 + ] - [Ca 2+ ] When [H + ] > 0: ‘real’ [H + ] When [H + ] < 0: [HCO 3 - ]

17. Number of years to deplete base cations in soil NE India 150(40 – 220) Malaysia110(40 – 160) S China17(6 – 35) Hicks et al. 2004

18. Sulfur

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

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

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

22. Nitrogen

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

24. S and N Future Emissions?

25. Global SO 2 emission scenarios (SRES) Tg S/yr 1990 2010 2030 2050 2070 2090 120 60 180 Nakicenovic et al. 2000

26. IPCC Special Report on Emissions Scenarios SO 2

27. 2000 2005 2010 2015 2020 2025 2030 Emissions of SO 2 from land-based sources in the 25 EU countries and from international shipping in European sea areas

28. IPCC Special Report on Emissions Scenarios NOx

29. N America Europe FSU China E Asia S Asia

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. From Wild et al. JGR June 2004 Contributions to ozone over Japan from Europe, US, East Asia and Japan Total European N American E Asian 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. Fig. 5. Simulated (top) and obs Extinction of sunlight due to aerosols in China Observations - JJA Model - JJA Qian et al. Tellus B 2003

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

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. 1.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) A subjective expert ”concern list” of air pollution issues at different scales:

47. Prospects for the future - Sulfur emissions: up in China, India.. down in Europe, US.. global total up - or down - NO x : up in many developing countries - NH 3 :? - 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