According to data published in 2013 by the International Energy Agency, coal is the most abundant fossil fuel. The IEA puts the total amount of proven coal resources available at 1,040 tons, which is up 3 percent from 2011.
The 1,040 tons of proven coal resources is good for 142 years of production at current rates. The IEA estimates that the total amount of coal resources is 20 times the number of proven coal resources, good for approximately 3,050 years of production. Natural gas comes in second with 61 years of proven resource production and 233 years of total estimated resource production. Oil comes in third with 54 years of proven resources for production and 178 years of total estimated resource production.