Now let’s consider what happens to all that CO2 that is emitted into the atmosphere. 
Of the 6 gigatons of carbon being put into the atmosphere every year by fossil fuel burning and the 1.5 gigatons being put there by deforestation (total 7.5 gigatons), only about 3 gigatons actually remains there. 
The amount remaining can be calculated directly from the increase in atmospheric CO2. 
So where is all the excess CO2 going?