Combustion of fossil fuels accounts for about 5% or so of the total release of CO2 into the atmosphere per year. Natural processes release and absorb many times that per year.
This is one of the dumbest 'arguments' of the anthropocentric truthers and bible throwers.
The natural process is a carbon
circulation. Combustion of fossil fuels takes carbon out of the ground and transfers it into the ocean and the atmosphere.