Wednesday, June 12, 2013

Beneficial effect of elevated CO2 on tree photosynthesis and growth is often further enhanced by warming

A new report from SPPI & CO2 Science:

[Illustrations, footnotes and references available in PDF version]
As the atmosphere's CO2 concentration continues to rise, most trees will likely exhibit increased rates of photosynthesis and biomass production, which can subsequently lead to an increase in the amount of timber that will likely be required to meet the growing needs of earth's expanding human population. However, some individuals have predicted that CO2-induced global warming will counteract the growth-promoting effects of atmospheric CO2 enrichment and actually reduce tree growth. Therefore, in order to determine if this widely-trumpeted claim has any validity, we turn to the peer-reviewed scientific literature to both report and summarize the results of several CO2-enrichment studies that were designed to reveal the concurrent effects of elevated CO2 and air temperature on the growth of trees and other woody plants.
The optimum growth temperature for several plants has already been shown to rise substantially with increasing levels of atmospheric CO2
The beneficial effects of elevated CO2 on tree photosynthesis and growth is often further enhanced by elevated air temperatures, which phenomenon can also be assessed during natural seasonal temperature changes.
In the face of rising atmospheric CO2 and temperature (global warming), trees will benefit from elevated CO2 through increased thermotolerance.
In regard to this hypothesis, such would indeed appear to be the case, in light of what is now the well-established fact that most woody plants tend to exhibit their greatest photosynthetic rates at increasingly warmer temperatures as the air's CO2 content continues to rise, as is confirmed by the many studies of this phenomenon discussed above. And in light of Jaramillo et al.'s findings, it is becoming ever more clear that greater warmth and atmospheric CO2concentrations are not the "twin evils" that the world's climate alarmists typically make them out to be. Quite to the contrary, they are just what earth's ecosystems need, in order to make them both more stable and more productive, which characteristics are absolutely essential for sustaining the still-increasing human population of the planet, as well as preserving what yet remains of what one could call wild nature.

In conclusion, the scientific literature of the past few decades continues to indicate that as the air's CO2 content rises, trees will likely exhibit enhanced rates of photosynthesis and biomass production that will not be negated by any global warming that might occur concurrently. In fact, if the ambient air temperature rises, the growth-promoting effects of atmospheric CO2 enrichment will likely rise right along with it. Thus, the future ability of earth's trees to produce greater amounts of biomass and, therefore, more timber products to meet the increasing needs of earth's expanding human population, looks promising indeed, just as long as the atmosphere's CO2 concentration continues to rise.

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