Global Carbon Cycle

1. Global Carbon Cycle • Ocean sequester ~30% of fossil fuel CO2 • Human perturbations overlay large natural background C cycle • Climate responses and feedbacks of ocean C sink not well known Sabine et al. (2004) SCOPE Feb 2004 Chemical Oceanography Seminar

2. 3

3. 4

6. Under IPCC “Business as Usual”the pH of surface sea water drops by 0.4 pH units by 2100. CO3= in surface water drops by 54% from pre-industrial values.  = [Ca2+][CO32-] Ksp' a > 1 ~ Supersaturated Average Surface Water DIC Increase in 2000 ~ 1.2 µmol kg-1 yr-1 2004 Hatfield Seminar

7. Air Increase = 1.48 ± 0.05 µatm yr-1; Seawater Increase = 2.48 ± 0.28 µatm yr-1 Dore et al., (2003)

8. WOCE/JGOFS/OACES Global CO2 Survey ~72,000 sample locations collected in the 1990s DIC ± 2 µmol kg-1 TA ± 4 µmol kg-1 Sabine et al (2004).

11. Global Anthropogenic CO2 Inventory = 118±19 Pg C Because the ocean mixes slowly, half of the anthropogenic CO2 stored in the oceans is found in the upper 10% of the ocean. Sabine et al. Science (2004)

12. Column inventory of anthropogenic CO2 that has accumulated in the ocean between 1800 and 1994 (mol m-2) Mapped Inventory 106±17 Pg C + marginal seas 6± 6 Pg C + Arctic Ocean 6± 6 Pg C Total Inventory 118±19 Pg C Sabine et al. Science (2004)

13. Carbon Changes Between 1800 and 1994 Over the past 200 years, the ocean has been the only reservoir to consistently take up anthropogenic CO2 from the atmosphere. Sabine et al. Science (2004)

14. Aragonite and Calcite Saturation Depths in the Global Oceans

15. Scanning electron micrographs of Emiliania huxleyi (left) and Geophyrocapsa oceanica (right) under conditions of 300 (top) and 780 - 850 ppm (bottom) pCO2 showing malformed coccospheres at the higher CO2 levels. From Riebesell et al. Nature (2001) 2004 Hatfield Seminar

16. Coccolithophores Forams calcite calcite T. Tyrrel Corals Calcareous algae aragonite High-Mg calcite 2004 Hatfield Seminar Nancy Sefton NOAA

17. Pteropods Clio pyramidata Cavolinia tridentata aragonite aragonite R. W. Gilmer and G. R. Harbison R. W. Gilmer and G. R. Harbison The effects of increased levels of CO2 on the dissolution of Clio pyramidata shells after 4 and 48 hours of exposure. 2004 Hatfield Seminar Victoria J. Fabry

18. From: R. Buddemeier

19. From: R. Buddemeier

20. From: R. Buddemeier