Most research has addressed how increasing atmospheric CO2 might affect terrestrial plants; indeed, some of that research illustrates the potential for positive effects through enhancement of plant growth (e.g., IPCC 1998; Rosenzweig and Hillel 1998). There is also the potential for increased CO2 levels to enhance phytoplankton growth and perhaps increase the overall productivity of the oceans, although the implications of this for oceanic ecosystems are uncertain.


There is evidence that coral reefs may be directly affected by increasing atmospheric CO2 entering the oceans (e.g., Kleypas et al. 1999; Wilkinson 1999) through effects on seawater chemistry and coral calcification rates. Evidence to support this includes:

  • The fact that latitudinal limits to reef development correlate not only with temperature, but with saturation state as well;

  • Geological evidence that aragonite sedimentation rates correlate latitudinally with changes in saturation states;

  • Geological evidence that Cainozoic coral reef development did not flourish until after the Eocene (the last geological period thought to have had unusually high atmospheric CO2 levels);

  • The observation that reef cements and other inorganic precipitates of CaCO3 are more prevalent in regions of high saturation states; and

  • Direct experiments that demonstrate the relationship between CaCO3 saturation state and coral / algal calcification (Joan Kleypas, quoted in Wilson 1999).

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Department of Environment and Heritage