Interannual extremes in the rate of rise of atmospheric carbon dioxide since 1980

• Published in: Nature (London) 1995-06, Vol.375 (6533), p.666-670
• Main Authors: Keeling, C. D, Whorf, T. P, Wahlen, M, van der Plichtt, J
• Format: Article
• Language: English
• Subjects: Atmosphere; Carbon dioxide; Chemical composition and interactions. Ionic interactions and processes; Earth, ocean, space; Exact sciences and technology; External geophysics; Humanities and Social Sciences; letter; Marine; Meteorology; multidisciplinary; Oceanography; Science; Science (multidisciplinary)
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/375666a0

OBSERVATIONS of atmospheric CO 2 concentrations at Mauna Loa, Hawaii, and at the South Pole over the past four decades show an approximate proportionality between the rising atmospheric concentrations and industrial CO 2 emissions 1 . This proportionality, which is most apparent during the first 20 years of the records, was disturbed in the 1980s by a disproportionately high rate of rise of atmospheric CO 2 , followed after 1988 by a pronounced slowing down of the growth rate. To probe the causes of these changes, we examine here the changes expected from the variations in the rates of industrial CO 2 emissions over this time 2 , and also from influences of climate such as El Niño events. We use the 13 C/ 12 C ratio of atmospheric CO 2 to distinguish the effects of interannual variations in biospheric and oceanic sources and sinks of carbon. We propose that the recent disproportionate rise and fall in CO 2 growth rate were caused mainly by interannual variations in global air temperature (which altered both the terrestrial biospheric and the oceanic carbon sinks), and possibly also by precipitation. We suggest that the anomalous climate-induced rise in CO 2 was partially masked by a slowing down in the growth rate of fossil-fuel combustion, and that the latter then exaggerated the subsequent climate-induced fall.