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Effects of global warming on the world’s oceans

Effects of global warming on the world’s oceans. Ashley A. Emerson. Anthropogenic CO 2 in the Ocean. CO 2 solubility. Temperature: more soluble at lower temperatures. Salinity: more soluble in greater salinity. Pressure: more soluble under higher pressure.

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Effects of global warming on the world’s oceans

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  1. Effects of global warming on the world’s oceans Ashley A. Emerson

  2. Anthropogenic CO2 in the Ocean

  3. CO2 solubility • Temperature: more soluble at lower temperatures. • Salinity: more soluble in greater salinity. • Pressure: more soluble under higher pressure.

  4. Carbon dioxide buffering in the Ocean • CO2 enters ocean via diffusion and rapidly converts to HCO3- • Reaction: CO2 + CO3 +H2O  2HCO3- • As CO2 in atmosphere rises the strength of ocean carbon uptake will weaken • Adding more carbon and keeping it as CO2 makes the ocean more acidic.

  5. Dissolved Inorganic Carbon (DIC) • CO2 reacts to form other compounds of DIC. • If in acidic solution: carbon in CO2 form • If in basic solution: carbon mostly in carbonate form • Ocean pH ~8 = Carbonate form

  6. Ocean acidification • By end of century, it is predicted that oceans surface-water DIC could decrease over 12% • Carbonate ion concentration decrease almost 60% • This would result in a pH drop in surface waters of 0.4 pH units

  7. Calcium carbonate budget Feely et al. 2004

  8. Impacts of anthropogenic CO2 on Calcium Carbonate • Aragonite and calcite undersaturation will occur at high latitudes when CO2 values reach 1200 and 1900 µatm • And at tropical/subtropical regions when CO2 values reach 1700 and 2800 µatm • Profound impacts on calcium carbonate shell-forming organisms

  9. Alkalinity • Determines pH and balances among forms of DIC • The sum of cation charges minus the sum of anion charges • Seawater is always positive, excess pos. charge • This is balanced by carbonate system  electrical neutrality CO3HCO3- CO2

  10. Carbonate Pump • Organic productivity is also associated with calcium carbonate production. • CaCO3 precipitation decreases alkalinity by 2 units (via removal of double-charged Ca++) but the total CO2 by only one unit (removal of CO3-) • Due to dominance of alkalinity change, there is a net shift of carbon towards CO2 CO3 -- HCO3- CO2 • Formation of CaCO3 therefore increases surface water CO2

  11. Ocean and atmosphere in the North Atlantic • Contribution of biological pump to anthropogenic carbon fluxes is very small everywhere except in high latitudes • High latitudes biological pump’s contribution is ~20% of the solubility pump. • The rate limiting step of anthropogenic CO2 uptake is ocean circulation and mixing.

  12. Other Factors to consider • Model shows as anthropogenic CO2 increases there will be reduced uptake of CO2 by oceans. • Primarily as a result of weakening of collapse of thermohaline circulation • El Niño events may be occurring more often as a result of increase anthropogenic CO2

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