Quote from AMT4SWA:
PLANTS and TREES (lush green wondrous living organisms........some that give off OXYGEN!!!) love CO2!!! 
Carbon dioxide (CO2) is the principal gas that trees and other plants need to survive, just like oxygen (O2) is the principal gas that humans and other animals require. Trees absorb CO2 and release O2 -- animals inhale O2 and exhale CO2. See how nice this all works! Earth's first, primitive forests made their prolific debut 300 million years ago during the Carboniferous Period. Before then, the atmosphere held far more CO2 but concentrations declined throughout the Carboniferous Period as plants flourished. During the Carboniferous Period the atmosphere became greatly depleted of CO2 (declining from about 2500 ppm to 350 ppm) so that by the end of the Carboniferous the CO2-impoverished atmosphere was less favorable to plant life and plant growth slowed dramatically.
Today, CO2 concentrations are barely at 380 ppm -- still CO2-impoverished. Many scientists strongly believe that we should be trying to produce more CO2, not less. And for good reason.
http://www.iloveco2.org/2009/01/co2-climate-facts.html
Atmospheric CO2 is 390 ppm not 380.
Many scientists do not believe that we should be producing more CO2. That is a straight barefaced lie. No national academy, scientific society or professional body has issued such a ludicrous recommendation. On the contrary they recommend strongly that CO2 emissions be curtailed to mitigate climate change.
Even the most casual home gardener is fully aware that more than CO2 is involved in plant growth - nutrients, soil structure, plants adapted to local climatic conditions and critically water are all vitally important.
It is true that higher levels of CO2 can promote plant growth, but what is good for the plants may very well not be good for humans or the rest of the ecosystem. The protein content of grains is significantly reduced and many plants produce increased toxins - cyanogens and phenols. Increased levels of toxins are already observed in cassava which is a staple food in large parts of the developing world. The health effects are horrible.
Under GHG induced climate change, and particularly regional effects such as increasing severity and frequency of drought, a bit of extra CO2 is not going to make a wit of difference to the food shortages induced by climate damage to food crops.
And then we could talk about ocean acidification and layering due to CO2 and rising temperatures. Increased layering is thought to be responsible for the
40% decrease in phytoplankton since 1950. Phytoplankton are the basis of the ocean food web and most life in the oceans. The mass of the phytoplankton is greater than all the forests on earth. They are plants too, and certainly do not seem to be prospering.
The author of the linked article is a crackpot, and the argument is simplistically stupid.
