When it comes to modelling terrestrial storage of carbon, the models account for the increasing effect of carbon dioxide fertilization (C), but they do not (except for two models) account for the effects of nitrogen fertilization (N) and none of them, phosphorus (P). (critical-angle.net)
Results showed that carbon dioxide fertilization explains 70 percent of the greening effect, said co-author Ranga Myneni, a professor in the Department of Earth and Environment at Boston University. (sciencedaily.com)
These facts help explain why, in spite of the Earth's air temperature increasing to a level that the IPCC claims is unprecedented in the the past millennium or more, a recent study by Randall et al. (2013) found that the 14 % extra carbon dioxide fertilization caused by human emissions between 1982 and 2010 caused an average worldwide increase in vegetation foliage by 11 % after adjusting the data for precipitation effects. (climatechangereconsidered.org)