What Is Causing Climate Change?
The concentration of CO2 in the atmosphere has increased from a preindustrial value of about 280 parts per million (ppm) to 379 ppm in 2005 (IPCC, 2007d). Most scenarios of future emissions of CO2 involve increases of CO2. In 2004, 26.9 billion metric tons of CO2 were emitted, and 33.9 billion metric tons are projected to be emitted in 2015. By 2030, 42.9 metric tons of CO2 are projected to be emitted (EIA, 2007).
References:
EIA (Energy Information Administration). 2007. International Energy Outlook 2007 (May 2007). DOE/EIA-0484(2007). accessed August 31, 2009.
IPCC. 2007d. Summary for Policymakers. In Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor, and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. accessed August 31, 2009.