Percentage of fossil fuel CO2 emissions that remain in the atmosphere, about 55%. Carbon dioxide mixing ratio measurements have been taken in Hawaii since 1958 by the research group of Charles David Keeling (1928-2005), a project initiated with support from Roger Revelle at Scripps Oceanographic Institute and Harry Wexler at the U.S. Weather Service. These data demonstrated that atmospheric carbon dioxide gas concentrations were increasing in the atmosphere and not just being absorbed by the ocean and plants. Atmospheric carbon dioxide gas phase concentration is lower during the spring when plants take up carbon dioxide and higher in the winter when the majority of plants are conserving energy, growing slower, and fallen plants are decaying and thus causing a rising fluctuation of carbon dioxide. [Atmospheric CO2 and 13CO2 exchange with the terrestrial biosphere and oceans from 1978 to 2000: observations and carbon cycle implications, pages 83-113, in "A History of Atmospheric CO2 and its effects on Plants, Animals, and Ecosystems", editors, Ehleringer, J.R., T. E. Cerling, M. D. Dearing, Springer Verlag, New York, 2005.] [Science; v307; 1869; 2005.