It is an intriguing exercise to examine the trends in carbon dioxide concentration in the atmosphere over the last two centuries. Variable Names: 1. Year: year 2. CO2 (ppm): atmospheric concentration of carbon dioxide, in parts per million Source: compiled by the WorldWatch Insitute from H. Friedli et al., "Ice Core Record of the 13C/12C ratio of Atmospheric CO2 in the Past Two Centuries," Nature, November 20, 1986; Charles D. Keeling and Timothy Whorf, Scripps Institute of Oceanography, La Jolla, CA, private communications, February 26, 1993 and February 14, 1994 private communication and printout, February 5, 1996. Atmospheric Concentrations of Carbon Dioxide Source: Worldwatch Institute - http://www.worldwatch.org Data structure: Year CO2 (ppm)