Read here. As has been well documented by many peer-reviewed studies, increases in atmospheric CO2 has done wonders for the biosphere and vegetation growth. The Amazon is just the most spectacular example.
"Gloor et al. conclude that their results lend "further support to the notion that currently observed biomass gains for intact forests across the Amazon are actually occurring over large scales at the current time, presumably as a response to climate change," which in many of their earlier papers is explicitly stated to include the aerial fertilization effect of the historical increase in the air's CO2 content."