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

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Presentation on theme: "Prof. Dudley Shallcross ACRG Tim Harrison Bristol ChemLabS 2008 A Pollutants Tale."— Presentation transcript:

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

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 : Natural & Man-made factors Observed simulated by model Temperature rise o C Hadley Centre

28 28 Impacts of Climate on the world: Temperature

29 29 Impacts of Climate on the World: Rainfall

30 Stabilisation Wedges

31 Billion of Tons of Carbon Emitted per Year Historical emissions 2105 The Stabilization Wedge – Two Scenarios

32 Billion of Tons of Carbon Emitted per Year 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

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

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

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


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