acclimation - elevated global temperatures reduce the rate of photosynthesis and plant growth.

 ne of the cruelties of global warming is that high concentrations of CO2 combined with elevated global temperatures reduce the rate of photosynthesis and plant growth. These effects are called “acclimation” and “heat stress” of plants, respectively.

Acclimation is either an enhancing or inhibiting effect on photosynthesis by high CO2 concentrations. Generally, photosynthesis is enhanced as CO2 concentration is increased from a low level. Then above an elevated threshold concentration, the rate of photosynthesis saturates and can even be reduced. The mechanism of the effect is involved and has been the subject of research for many years by agricultural scientists interested in maximizing crop yields (for example in greenhouses).

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Current research on plant growth under the combined effects of elevated temperature and high CO2 concentration shows that “in heat-stressed plants at normal or warmer growth temperatures, high CO2 may often decrease, or not benefit as expected, tolerance of photosynthesis to acute heat stress. Therefore, interactive effects of elevated CO2 and warmer growth temperatures on acute heat tolerance may contribute to future changes in plant productivity, distribution, and diversity.”