How does rising atmospheric CO2 affect marine organisms?

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Clarifying the Interactive Effects of Elevated CO2 and Temperature on Photosynthesis
Reference
Cannell, M.G.R. and Thornley, J.H.M.  1998.  Temperature and CO2 responses of leaf and canopy photosynthesis: a clarification using the non-rectangular hyperbola model of photosynthesis.  Annals of Botany 82: 883-892.

What was done
The authors explored the effects of elevated CO2 and temperature on C3 photosynthesis using data obtained from the published literature in conjunction with a non-rectangular hyperbolic photosynthetic model that is driven primarily by quantum yield and light-saturated photosynthetic rate.

What was learned
Based on model output, the authors determined that a doubling of the atmospheric CO2 concentration may substantially raise the temperature optimum for photosynthesis at warm, but not cool, temperatures.  In addition, twice-ambient CO2 concentrations increased maximum rates of photosynthesis by 61, 89, and 133% in response to a 2, 5, and 10°C increase in the ambient air temperature, which in this instance was 28°C.

What it means
As the air's CO2 content rises, it will likely increase rates of photosynthesis, particularly in C3 plants, which should thus lead to increases in plant biomass.  Moreover, if ambient air temperatures also increase, these phenomena will likely increase for that reason too.  Consequently, terrestrial carbon sequestration will likely increase even more in a CO2-enriched world if air temperatures rise concurrently, particularly in warmer climates.


Reviewed 18 December 2002