The process consumes O2<\/sub> and produces CO2<\/sub>. Because the additional atmospheric CO2<\/sub> is accompanied by a measurable decline in atmospheric O2<\/sub>, the observations are consistent with large-scale combustion of carbon rather than simply a redistribution of carbon through the natural carbon cycle.<\/p>\n This is especially important because the ocean, vegetation, and atmosphere continuously exchange carbon and oxygen. Natural processes can move carbon between reservoirs, but they do not explain the simultaneous long-term pattern of rising CO2<\/sub>, falling O2<\/sub>, declining 13<\/sup>C\/12<\/sup>C, and declining radiocarbon.<\/p>\n The four observations reinforce one another:<\/p>\n \n Rising atmospheric CO2<\/sub> Together, these measurements provide a chemical and isotopic fingerprint of fossil-carbon combustion.<\/p>\n Volcanoes do not produce the observed isotopic pattern, and the natural carbon cycle cannot account for the simultaneous changes in the required direction and magnitude.<\/p>\n The molecules carry their own fingerprint—and the atmosphere is preserving the evidence in both carbon and oxygen.<\/strong><\/p>\n
\n ![\"Anthropogenic](\"\/global_warming\/climate-graphics\/O2-Combustion-Fingerprint.jpg\")
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\n Declining 13<\/sup>C\/12<\/sup>C
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\n Declining 14<\/sup>C
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\n Declining atmospheric O2<\/sub>\n<\/p>\nAnthropogenic Global Warming 101<\/a><\/h3>\n