THE WORLD MAY NEVER DOUBLE THE AMONUNT OF CO2 IN THE ATMOSPHERE

This article explains why. The conclusion of the article is that, given the latest projections of CO2 emissions, future CO2 concentrations will not only be well below the highest predictions, but might not be as high as the lower ones, with atmospheric CO2 concentrations not even reaching a doubling (560 ppm) of pre-industrial levels (280 ppm) before levelling off.