CO2 fertilization

As described in Chapter 6, CO₂ fertilization is the process by which the growth rate of certain trees is increased due to increased concentration of carbon dioxide in the air. Some scientists believe that the increased rate of photosynthesis and the formation of greater amounts of fixed carbon represent a sink for CO₂. However, several experiments described here: http://www.realclimate.org/index.php/archives/2004/11/co_2-fertilization/ provide a different perspective. Experiments and models have shown that although CO₂ fertilization can cause a temporary increase in biomass, it is not likely to offset increases in CO₂ from anthropogenic sources. In models where availability of carbon to plants is not constrained, other conditions, such as the availability of certain nutrients, still limit the production of biomass. The article claims that based on minimum projected emissions of 600 billion tons of carbon for the 21^st century, it is not likely that increased vegetation could account for more than a few percent of these emissions. .