1. Changes in Atmospheric Constituents and in Radiative Forcing Part I Stautzebach Elena

2. Summary Introduction: - What is radiative forcing? - Why is radiative forcing relevant for climate change? Part 1: Anthropogenic Greenhouse Gases - Atmospheric Carbon Dioxide - Atmospheric Methane - Other Kyoto Protocol Gases - Montreal Protocol Gases - Ozone - Stratospheric Water Vapour Part 2: Aerosols - Direct radiative effects - Indirect effects (Cloud Albedo Effect)

3. What is Radiative Forcing? ΔTs = λ ∙ RF

4. Components of the Climate Change Process

5. Part 1 Anthropogenic Greenhouse Gases

6. Most important greenhouse gases Carbon dioxide (CO 2 ) Methane (CH 4 ) Other Kyoto Protocol Gases: N 2 O; PFCs; HFCs; SF 6 Montreal Protocol Gases: CFCs; HCFCs… Ozone Stratospheric water vapour

7. Carbon dioxide (CO 2 ) Sources use of fossil fuel in transportation building heating and cooling manufacture of cement Deforestation

8. Carbon dioxide (CO 2 ) Radiative Forcing calculations: - CO 2 reference level - recent changes in atmospheric mixing ratios  Different methods for CO 2 –measurements: - In situ continuous measurements - Air sample flask programs - Isotope ratio mass spectrometry - Atmospheric O 2 measurements

9. In situ continuous measurements Continuous measurements at Mauna Loa, Hawaii since 1958

10. Air sample flask programs to supplement in situ measurement to estimate sources and sinks National Oceanic and Atmospheric Administration’s Global Monitoring Division in the USA Isotope ratio mass spectrometry Measures especially CO 2 emissions from fossil fuel combustion

11. Atmospheric O 2 measurements Atmospheric O 2 and CO 2 changes are inversely coupled during plant respiration and photosynthesis

12. Results Increase of 100 ppm over the last 250 years CO 2 emissions due to fossil fuel combustion and cement manufacture have increased by 70% over the last 30 years radiative forcing is estimated of 1,66 ± 0,17 W/m² ¾ of the current radiative forcing is due to fossil fuel and cement production

13. Methane (CH 4 ) Sources wetlands rice agriculture biomass burning emissions from living vegetation fossil fuel mining  Sources are well known but the strength of each source component is not

14. Methane Historical evolution In the last 650 kyr: - lows of about 400ppb during glacial periods - - highs of about 700ppb during interglacial periods (770 ppb at Vostok) Between 1700 and 1800: global value of 714 ± 4ppb

15. Methane (CH 4 ) Increase of about 30% in the last 25 years growth rate has decreased substantially growth rate shows large anomalies

16. Results In 2005 CH 4 mixing ratio is at 1774ppb Radiative Forcing of +0,48 ± 0,05 W/m²  CH 4 is the second highest radiative forcing after CO 2

17. Other Kyoto Protocol Gases N 2 O rapid rise in the last 200 years Since 1998 N 2 O levels have risen to 319 ± 0,12ppb in 2005 radiative forcing of +0,16 ± 0,02 W/m²

18. Other Kyoto Protocol Gases PFCs HFCs SF 6 very effective absorbers of infrared radiation  even small amounts contribute significantly to the radiative forcing of the climate system

19. Montreal Protocol Gases = international treaty on substances that deplete the ozone layer CFCs, HCFCs, chlorocarbons, bromocarbons, halons Since Montreal Protocol decrease of CFC-11 and CFC-113, stagnation of CFC-12

20. Ozone Stratospheric Ozone Ozone hole over Antarctica NH: 30% of the ozone trends are related to dynamical effects temporally and seasonally changes total stratospheric ozone RF is -0,05 ± 0,10 W/m² since pre-industrial time Tropospheric Ozone regional differences: - decrease in industrialized regions - Increase in developing countries RF increased by 0,35W/m² since pre- industrial time

21. Stratospheric Water Vapour long-term increase Forcing mechanisms: - volcanic eruptions - biomass burning aerosol - changes in CH 4 oxidation rates - injection of water vapour by aircraft Mechanisms not linked to an external forcing agent: - changes in tropopause temperatures or circulation  RF: +0,07 ± 0,05 W/m².

22. Part 2 Aerosols

23. Direct Effects mechanism by which aerosols scatter and absorb shortwave and longwave radiation Indirect effects mechanism by which aersols modify the microphysical and radiative properties of clouds Cloud albedo effect Cloud lifetime effect Semi-direct Effects heating of the troposphere and therefore influences cloud formation and lifetime

24. Seasonal variability of the aerosol optical depth

25. DIRECT EFFECTS

26. Direct radiative effect Reference Instrument a Data Analysed Clear Sky DRE(W m –2 ) ocean Bellouin et al. (2005) t MODIS; TOMS; SSM/I 2002 –6.8 Loeb and Manalo-Smith (2005) CERES; MODIS Mar 2000 to Dec 2003 –3.8 (NESDIS)to –5.5 (MODIS) Remer and Kaufman (2006) MODIS Aug 2001 to Dec 2003 –5.7 ± 0.4 Zhang et al. (2005); Christopher and Zhang (2004) CERES; MODIS Nov 2000 to Aug 2001 –5.3 ± 1.7 Bellouin et al. (2003) POLDER Nov 1996 to Jun 1997 –5.2 Loeb and Kato (2002) CERES; VIRS Jan 1998 to Aug 1998; Mar 2000. –4.6 ± 1.0 Chou et al. (2002) SeaWiFs 1998 –5.4 Boucher and Tanré (2000) POLDER Nov 1996 to Jun 1997 –5 to –6 Haywood et al. (1999) ERBE Jul 1987 to Dec 1988 –6.7 Mean (standard deviation) –5.4 (0.9)

27. Radiative Forcing for Combined Total Aerosol Sulphate Aerosol: -0,4 ± 0,2 W/m² Organic Carbon Aerosol from Fossil Fuels: -0,05 ± 0,05 W/m² Black Carbon Aerosol from Fossil Fuels: +0,2 ± 0,15 W/m² Biomass Burning Aerosol: +0,03 ± 0,12 W/m² Nitrate Aerosol: -0,1 ± 0,1 W/m² Mineral Dust Aerosol: -0,1 ± 0,2 W/m²  Combined aerosol direct Radiative Forcing: -0,5 ± 0,4 W/m²

28. INDIRECT EFFECT

29. Indirect Radiative Forcing Link between Aerosol particles and cloud microphysics Nonlinear relationsship between aerosols and cloud droplet number concentrations: N d = N a b Aerosols mostly consist of internal mixture Size of the particle is more important than the composition Radiation transfer in cold clouds depending on insoluble particles within the ice crystals

30. Radiative Forcing from Cloud Albedo Effect RF estimation: -0,7 W/m² as the median, with a 5 to 95% range of -0,3 to -1,8 W/m² Increase in the knowledge of the aerosol- cloud interactions since the TAR result  Elevation of the level of scientific understanding to low

31. Part 3 Conclusion

33. THANK YOU FOR YOUR ATTENTION!