Hi All, I thought you might be interested in the below article from Science News. Global warming is real, but it may be cyclical beyond our control, especially now that methane is being released from the melting tundra -- probably a deviation amplifying process.
Maybe we should be grateful for anything that puts greenhouse gas into the atmosphere because we may be entering the cooling phase of the Milankovitch cycle. Jack Smith ------------ Science News, Vol. 170, No. 16, Oct. 14, 2006, p. 253. by Sid Perkins http://www.sciencenews.org/articles/20061014/note11.asp ``Ancient hot spell is linked to copious carbon dioxide The presence of a particular mineral in ancient rock suggests that during an extended warm period in Earth's past, the atmosphere held at least triple the concentration of carbon dioxide that it does today, a new analysis shows. Between 52 million and 50 million years ago, Earth's climate was the warmest it had been since the dinosaurs died out 65 million years ago. The temperature of the deepest water in the oceans, an indication of global climate, was at least 10°C higher than it is today. Some rocks derived from Colorado lake sediments of that era contain large amounts of nahcolite, a natural form of baking soda. Lab tests indicate that nahcolite would precipitate out of salty, alkaline lakes only if atmospheric concentrations of carbon dioxide were above 1,125 parts per million (ppm), Tim K. Lowenstein and Robert V. Demicco of the State University of New York at Binghamton report in the Sept. 29 Science. Today, concentrations of that greenhouse gas measure about 380 ppm, Lowenstein notes. The climate around the ancient lake where these minerals formed was probably similar to that at the Dead Sea today, says Lowenstein. There, air temperatures average 24°C and surface-water temperatures range from 21°C to 36°C. '' References: Lowenstein, T.K., and R.V. Demicco. 2006. Elevated eocene atmospheric CO2 and its subsequent decline. Science 313(Sept. 29):1928. Abstract available at http://www.sciencemag.org/cgi/content/abstract/313/5795/1928. Sources: Tim K. Lowenstein Department of Geological Sciences and Environmental Studies State University of New York, Binghamton Binghamton, NY 13902 >From Science News, Vol. 170, No. 16, Oct. 14, 2006, p. 253. ----------------- Science 29 September 2006: Vol. 313. no. 5795, p. 1928 DOI: 10.1126/science.1129555 Abstract ``Elevated Eocene Atmospheric CO2 and Its Subsequent Decline by Tim K. Lowenstein* and Robert V. Demicco Quantification of the atmospheric concentration of CO2 ([CO2]atm) during warm periods of Earth's history is important because burning of fossil fuels may produce future [CO2]atm approaching 1000 parts per million by volume (ppm). The early Eocene (~56 to 49 million years ago) had the highest prolonged global temperatures of the past 65 million years. High Eocene [CO2]atm is established from sodium carbonate minerals formed in saline lakes and preserved in the Green River Formation, western United States. Coprecipitation of nahcolite (NaHCO3) and halite (NaCl) from surface waters in contact with the atmosphere indicates [CO2]atm > 1125 ppm (four times preindustrial concentrations), which confirms that high [CO2]atm coincided with Eocene warmth. '' Department of Geological Sciences and Environmental Studies, State University of New York at Binghamton, Binghamton, NY 13902, USA. * To whom correspondence should be addressed. E-mail: lowenst{at}binghamton.edu
