Co2 concentrations on earth:
1958: 315 parts per million (ppm) : raised 0.7 ppm per year
2014/15: 400 ppm : raised 2.1 ppm per year
As a rule of thumb, CO2 concentrations will have to be restricted to about 450ppm if global warming is to be kept below 2°C (a level that might possibly be safe). Because CO2 stays in the atmosphere for decades, artificial emissions of the gas would have to be cut immediately, and then fall to zero by 2075, in order to achieve 450ppm. There seems no chance of that. Emissions are still going up. At current rates, the Mauna Loa observatory, Hawaii reading will rise above 450 ppm in 2037.
*Results taken from world's longest observations on carbon emissions