Fossil fuels are fuels containing carbon – coal, oil and gas – that were formed over millions of years through the decay, burial and compaction of rotting vegetation on land, and of marine organisms on the sea floor. Burning fossil fuels is the major way in which humans add to the greenhouse gases in the atmosphere.

World Fossil fuels consumption between 1965 and 2005

 

Over the last 50 years, while consumption of fossil fuels grew substantially, the world undertook a transition in its usage of fossil fuels, from solids (coal), to liquids (oil) to gases (natural gas). While coal accounted for 62% of all fossil fuel consumption in 1950, this share dropped to 28% in 1998 equivalent to the share of natural gas. The share of oil substantially increased between 1950 and 1980, where it peaked at 45% of fossil fuel use, then declined to 43%.