AFP: More plant growth could slow global warming: NASA

WASHINGTON — In a world with twice as much carbon dioxide in the atmosphere, plants could grow larger and create a cooling effect on a warming globe, but could not halt or reverse climate change, NASA said Tuesday.
...
NASA's new computer modeling effort, described in the December 7 issue of the journal Geophysical Research Letters, calculated the plants' cooling effect to be -0.3 degrees Celsius (-0.5 Fahrenheit) globally.