How can we calculate the amount of carbon dioxide released into the atmosphere as a result of human activity?

Each year about 30 billion barrels of oil are consumed globally. A barrel of oil has a mass of approximately 135 kg and is made up of a mix of hydrocarbon chains of various lengths that release carbon dioxide into the atmosphere when burned.

Question: How many kilograms of carbon are released when one barrel of oil undergoes a combustion reaction? Assume that the average chemical formula for oil is C₈H₁₈ (octane).

First, we must balance the chemical formula for the combustion of octane:

We can use stoichiometry to calculate the kilograms of carbon released per 135 kg barrel of oil. First, we will convert the mass of C₈H₁₈ into moles:

Now we can calculate kg of carbon released into the atmosphere using the moles of C₈H₁₈ we calculated previously:

Close to 113 kg of carbon is released into the atmosphere each time a barrel of oil is burned!

Question: Calculate the amount of carbon, in metric tonnes (1000 kg = 1 ton), released by the human race each year due to the combustion of approximately 30 billion barrels of oil.