Some back of a fag packet calculations:
Proven oil reserves approx 1,000,000,000,000 barrels = 100,000,600,000,000 kg. Given low weight of hydrogen component, call this carbon content
Proven coal reserves = 847,000,000,000,000kg
Therefore total carbon content of fossil reserves approx 1,000,000,000,000,000 kg
Burn this, then we generate approx 3,000,000,000,000,000 kg of CO2
Current mass of CO2 in atmosphere = 3,000,000,000,000,000 kg
Therefore burn all proven resources and amount of CO2 in atmosphere is doubled.
May have misplaced a 0 somewhere, so other fag packet calculations welcome for comparison.
Robin