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Effects of Atmospheric CO2 Enrichment on Photosynthesis in Norway Spruce Trees
Reference
Roberntz, P.  2001.  Atmospheric carbon dioxide concentration, nitrogen availability, temperature and the photosynthetic capacity of current-year Norway spruce shoots.  Tree Physiology 21: 931-940.

What was done
The authors measured gas exchange rates of current-year needles on 30-year-old Norway spruce (Picea abies L.) seedlings that had individual branches exposed to ambient and elevated (ambient plus 350 ppm) concentrations of atmospheric CO2 within plastic branch bags to determine the effects of elevated CO2 on photosynthesis.

What was learned
Atmospheric CO2 enrichment enhanced rates of net photosynthesis by 20 to 75% in current-year needles.  In addition, elevated CO2 increased the optimum temperature for photosynthesis by 4.1°C.

What it means
As the air's CO2 content rises, it is likely that Norway spruce trees will exhibit increased rates of photosynthesis that will likely contribute to greater biomass production.  In addition, it is likely that the optimum temperature for photosynthesis in this important forest species will also rise.  Hence, even if the air temperature were to rise as predicted by state-of-the-art climate models, there would be no compelling physiological reason for Norway spruce trees to migrate either upward in altitude or poleward in latitude.  They could do so; but they would not need to do so.  Consequently, instead of the horror of extinction that is so frequently put forth as a sure bet by climate alarmists if the air's CO2 content continues to rise, we are much more likely to see increases in ecosystem biodiversity, as more species acquire the ability to live in temperature regimes to which they are currently unsuited, which would allow them to significantly extend their ranges.