1. CO 2 fertilization (increased water use efficiency). Plants take in carbon dioxide and lose water vapor through small pores in their leaves called stomata. Under elevated carbon dioxide levels the pores become smaller and the plant loses less water. This makes photosynthesis more efficient, and the plants can assimilate carbon more rapidly.

2. Methane sources and sinks (Lowe 2006) (Mt CH 4 yr -1 )

3. Known sources and sinks of atmospheric CH 4 1990 – 2000 Atmospheric life time ~ 9 years wetlands termites Ocean hydrates Total~ 600 Tg(CH 4 /y) Biomass burning Natural sources Energy Domestic waste Ruminants Rice paddies Transport to stratosphere Oxidation in soils Tropospheric OH Sources [Tg/yr]Sinks [Tg/yr]

7. Methane sources and sinks (Lowe 2006) (Mt CH 4 yr -1 )

10. (present relative to 1750)

11. Greenhouse gas global warming potentials (100 year time horizon)

12. Methane sources and sinks (Lowe 2006) (Mt CH 4 yr -1 )

13. SourceFlux (MtCyr -1 )Flux (GtC equivalent yr -1 ) microbes in wetlands92-237 (IPCC 2001)2.12-5.45 ruminants and termites100-135 (IPCC 2001)2.30-3.11 anthropogenic170-340 (IPCC 2001)3.91-7.82 Methane (CH 4 ) production: CH 4 has 23 times the greenhouse potential of CO 2 Anthropogenic carbon dioxide emissions about 7GtC/yr

14. Measured methane emissions (Frankenberg et al. 2005)

15. Methane emissions (Tg CH4) per source category as used in the TM3 model for the period August through November 2003 and for the whole year (between brackets). Frankenberg et al. 2005

17. Simulated methane emissions (Frankenberg et al. 2005)

18. Difference between measured and simulated methane emissions (Frankenberg et al. 2005)

21. Emissions from living plants

22. Plant litter

23. Exclude biological activity

24. Summary living plants 9 plant species (C3 and C4) 18 l volume incubation chambers dependence on sunlight typical emission rates: 12 to 370 ng g(dw) -1 h -1 grown on soil and hydroponically

25. Global extrapolation

26. SourceFlux (MtCyr -1 )Flux (GtC equivalent yr -1 ) plants63-243 (Keppler et al 2006) 1.45-5.59 microbes in wetlands92-237 (IPCC 2001)2.12-5.45 ruminants and termites100-135 (IPCC 2001)2.30-3.11 anthropogenic170-340 (IPCC 2001)3.91-7.82 Methane (CH 4 ) production: CH 4 has 23 times the greenhouse potential of CO 2

27. Sources of atmospheric carbon Respiration (autotrophic and heterotrophic) Burning of fossil fuels – over past 2 centuries, source of 480-500 Gt (Pg) C (IPCC 2001) comparable in size to terrestrial plant pool – current rate: 5.3 GtCyr -1 (IPCC 2001) Natural fires Outgassing of CO 2 : – from fresh water: 0.9 GtCyr -1 (Richey et al 2002) – from ocean – from soils Methane (CH 4 ) production: – CH 4 has 23 times the greenhouse potential of CO 2 SourceFlux (MtCyr -1 )Flux (GtC equivalent yr -1 ) plants63-243 (Keppler et al 2006)1.45-5.59 microbes in wetlands92-237 (IPCC 2001)2.12-5.45 ruminants and termites100-135 (IPCC 2001)2.30-3.11 anthropogenic170-340 (IPCC 2001)3.91-7.82

28. CH4 trend NOAA Source: NOAA/CMDL [ http://www.cmdl.noaa.gov] 12.3% reduction in tropical forests between 1990 and 2000  6-20 Tg CH 4 yr -1 Source-sink imbalance 14 Tg yr -1 (IPCC)