The composition of U.S. energy use, 1800-2000. Fire transformed human life by providing light, warmth, cooking, healing and ultimately the ability to smelt and forge metals, and to bake bricks, ceramics, and lime. Fire became the basis for the Greek culture and ultimately all Western culture.

The changes wrought by fossil fuels exceeded even those produced by the introduction of fire. The rapid expansion of the human population and its material living standard over the past 200 years could not have been produced by direct solar energy and wood being converted by plants, humans and draft animals. Advances in every human sphere—commerce, agriculture, transportation, the military, science and technology, household life, health care, public utilities—were driven directly or indirectly by the changes in society's underlying energy systems.

In the coming decades, world oil production will peak and then begin to decline, followed by natural gas and eventually coal production. The precise nature of the energy transition is uncertain, but its sheer magnitude will dwarf the wood-to-coal transition of the 19th century. More importantly, the next energy transition will occur under a very different set of conditions. Solar energy and wind are inherently lower quality than fossil fuels, and the global environmental frontier is closed. In addition, future energy systems must supply adequate energy to support the high and still growing living standards in wealthy nations, and they must supply energy sufficient to relieve the abject poverty of the world's poorest.

Sources

• Cleveland, Cutler, Energy transitions past and future. In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). Accessed January 26, 2008.
• Grubler, Arnulf (Lead Author); Cutler J. Cleveland (Topic Editor). 2008. Energy transitions.  In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth August 29, 2006; Last revised June 3, 2008; Retrieved September 29, 2008]. 
• Smil, Vaclav. 2006. 21st century energy: Some sobering thoughts. OECD Observer 258/59: 22-23.