1. The Ocean’s Role in the Carbon Cycle in Relation to Increased Atmospheric CO 2 Paul Loikith

2. CO 2 and the Ocean The ocean is both a source and sink for carbon dioxide The ocean is both a source and sink for carbon dioxide With increasing CO 2 concentrations, there is more dissolved inorganic carbon in the ocean With increasing CO 2 concentrations, there is more dissolved inorganic carbon in the ocean Ocean becomes more acidic with increasing dissolved carbon dioxide Ocean becomes more acidic with increasing dissolved carbon dioxide

3. CO 2 and the Ocean Before industrial era, ocean controlled CO 2 concentrations in the atmosphere Before industrial era, ocean controlled CO 2 concentrations in the atmosphere DIC concentrations are 50 times higher in the oceans than the atmosphere DIC concentrations are 50 times higher in the oceans than the atmosphere Rates of absorption are highest in cold/saline water with overturning Rates of absorption are highest in cold/saline water with overturning

4. CO 2 and pH IPCC Working Group I (2007)

5. Increasing DIC 118 +- 19 GtC increase between pre- industrial times and 1994 of DIC in oceans 118 +- 19 GtC increase between pre- industrial times and 1994 of DIC in oceans Ocean is a sink for approx. 30-50% of atmospheric anthropogenic CO 2 Ocean is a sink for approx. 30-50% of atmospheric anthropogenic CO 2

6. Consequences of Global Warming on CO 2 and Oceans Stratified oceans have decreased intake of CO 2 Stratified oceans have decreased intake of CO 2 Warming world, less DIC uptake in oceans Warming world, less DIC uptake in oceans Decreasing pH of oceans Decreasing pH of oceans Changing densities of Southern Oceans – less uptake Changing densities of Southern Oceans – less uptake Changes in overturning and THC – changes in uptake Changes in overturning and THC – changes in uptake

7. Conclusions Increasing atmospheric CO 2 will lead to increasing concentrations in ocean Increasing atmospheric CO 2 will lead to increasing concentrations in ocean Lower pH will result, biological consequences Lower pH will result, biological consequences Changes in ocean circulations could decrease rate of intake of carbon, even more in atmosphere (positive feedback) Changes in ocean circulations could decrease rate of intake of carbon, even more in atmosphere (positive feedback)

8. Sources Caldeira, K., P. B. Duffy, 2000: The Role of the Southern Ocean in Uptake and Storage of Anthropogenic Carbon Dioxide. Science, 287, 620-622. Caldeira, K., P. B. Duffy, 2000: The Role of the Southern Ocean in Uptake and Storage of Anthropogenic Carbon Dioxide. Science, 287, 620-622. Falkowski, P., et al., 2000: The Global Carbon Cycle: The Test of Our Knowledge of Earth as a System. Science, 290, 291-296. Falkowski, P., et al., 2000: The Global Carbon Cycle: The Test of Our Knowledge of Earth as a System. Science, 290, 291-296. IPCC Report. Working Group 1. Chapter 5 2007. IPCC Report. Working Group 1. Chapter 5 2007.