Most energy used to meet human needs is derived from the combustion of fossil fuels (natural gas, oil, and coal), which releases carbon to the atmosphere, primarily as carbon dioxide (CO₂). The atmospheric concentration of CO₂, a greenhouse gas, is increasing, raising concerns that solar heat will be trapped and the average surficial temperature of the Earth will rise in response. Global warming studies predict that climate changes resulting from increases in atmospheric CO₂ will adversely affect life on Earth.

In the 200 years since the industrial revolution, the world's population has grown from about 800 million to over 6 billion people and the CO₂ content of the atmosphere has risen from about 280 to about 360 parts per million by volume, a 30 percent increase. International concern about potential global climate change has spurred discussions about limiting the amount of CO₂ and other greenhouse gases released to the atmosphere.