1. Prof. Dudley Shallcross ACRG Tim Harrison Bristol ChemLabS 2008 A Pollutants Tale

2. 2 Talk outline Comparison of the Earth with other planets Nitrogen and oxygen Temperature structure Tropospheric pollutants

3. 3

4. 4 Nitrogen N N bond energy = 944 kJ/mol 78% of the atmosphere inert Gas at 25 O C, liquid at – 196 O C TGH

5. 5 Bacterial scrapheap challenge by Dr. Hazel Mottram

6. 6 Oxygen O=O bond energy = 496 kJ/mol 21% of the atmosphere Gas at 25 O C, liquid at -183 O C Photosynthesis is the main source of O 2 6CO 2 + 6H 2 O + sunlight C 6 H 12 O 6 + 6O 2 2H 2 O 2 2H 2 O + O 2 TGH

7. 7 Life spring by Dr. Adrian Mulholland

8. 8

9. 9 Urban Atmospheric Chemistry 10 km NO, NO 2, VOC VOCs ? 0 km Compounds of both biogenic and anthropogenic origin 1 km The Tropopause The Boundary Layer

10. 10 What happens to VOCs (volatile organic compounds)? Plants and trees emit a vast range of organic material; alkenes, alcohols, carbonyls, acids Vehicles emit hydrocarbons and aromatic species Many of these species are insoluble and are not rained out, how are they removed? TGH

11. 11 High temperature combustion VOCs can be burned in air (combustion) and oxidised in the process CaC 2 + 2H 2 O Ca(OH) 2 + C 2 H 2 C 2 H 2 + (5/2)O 2 2CO 2 + H 2 O CH 3 OH + (3/2)O 2 CO 2 + 2H 2 O The atmosphere oxidises VOCs using free radicals

12. 12 VOCs broken down by the OH radical, generated by sunlight

13. 13 Air measurements in Bristol of NO 2 Data from 21 st January 2001: Combustion is the main source of NO 2 TGH

14. 14 NO 2 + sunlight O * + NO < ~ 400 nm O* + O 2 O 3 TGH Photochemical smog

15. 15 Photochemical smog in Bristol: 27/07/2001

16. 16 CO 2 measurements in Bristol CO 2 has been measured for several years at the top of Old Park Hill.

17. 17 CO 2 measurements at Bristol

18. 18 Longer term CO 2 measurements CO 2 measurements have been made at Mauna Loa for many many years, and show that CO 2 has been rising steadily for some time

19. 19 The enhanced greenhouse effect

20. 20 Secrets in the Ice Snow accumulation lays down record of environmental conditions Compacted to ice preserving record Drill ice core & date Secrets in the Ice

21. 21 CO 2 levels over the last 1000 years Gases are extracted from bubbles trapped in ice cores and provide record of past atmospheric concentrations

22. 22 Frog chorus by Dr. Simon Hall

23. 23 Methane (CH 4 ) and Nitrous Oxide (N 2 O)

24. 24 Increased global temperature

25. 25 Impacts of global warming Impacts associated with changes in –Precipitation –Sea level –Extreme weather 1941 2004

26. 26 Model simulation of recent climate Natural forcings only (solar, volcanic etc. variability) Anthropogenic forcings only (human-induced changes) The Met Office

27. 27 Simulated global warming 1860-2000: Natural & Man-made factors Observed simulated by model Temperature rise o C 0.0 0.5 1.0 1850 1900 1950 2000 Hadley Centre

28. 28 Impacts of Climate on the world: Temperature

29. 29 Impacts of Climate on the World: Rainfall

30. Stabilisation Wedges

31. 20552005 14 7 Billion of Tons of Carbon Emitted per Year 1955 0 Historical emissions 2105 The Stabilization Wedge – Two Scenarios

32. 20552005 14 7 Billion of Tons of Carbon Emitted per Year 1955 0 Historical emissions 2105 The Stabilization Wedge – Two Scenarios

33. 14 7 Billion of Tons of Carbon Emitted per Year 0 Historical emissions Currently projected path Flat path 20552005 1955 2105

34. 14 7 Billion of Tons of Carbon Emitted per Year 0 Stabilization Triangle Currently projected path Flat path Historical emissions Easier CO 2 target ~850 ppm Tougher CO 2 target ~500 ppm 20552005 1955 2105

35. 14 7 Billion of Tons of Carbon Emitted per Year 0 Currently projected path Flat path Historical emissions 14 GtC/y 7 GtC/y Seven wedges 20552005 1955 2105

36. Current technology options to provide a wedge Improve fuel economy Reduce reliance on cars More efficient buildings Improved power plant efficiency Decarbonisation of Electricity and Fuels Substitution of Natural gas for coal Carbon capture and storage Nuclear fission Wind electricity Photovoltaic electricity Biofuels

37. 37

38. 38 Thanks to Bristol ChemLabS British Council Sci Fest Africa 2008 t.g.harrison@bris.ac.uk d.e.shallcross@bris.ac.uk www.chemlabs.bris.ac.uk/outreach