The Ocean

1
The Oceans Role in the Carbon Cycle in Relation
to Increased Atmospheric CO2

• Paul Loikith

2
CO2 and the Ocean

• The ocean is both a source and sink for carbon
  dioxide
• With increasing CO2 concentrations, there is more
  dissolved inorganic carbon in the ocean
• Ocean becomes more acidic with increasing
  dissolved carbon dioxide

3
CO2 and the Ocean

• Before industrial era, ocean controlled CO2
  concentrations in 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

4
CO2 and pH
IPCC Working Group I (2007)
5
Increasing DIC

• 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 CO2

6
Consequences of Global Warming on CO2 and Oceans

• Stratified oceans have decreased intake of CO2
• Warming world, less DIC uptake in oceans
• Decreasing pH of oceans
• Changing densities of Southern Oceans less
  uptake
• Changes in overturning and THC changes in uptake

7
Conclusions

• Increasing atmospheric CO2 will lead to
  increasing concentrations in ocean
• Lower pH will result, biological consequences
• 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.
• 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.