_:genid1 . _:genid1 "Unknown" . _:genid2 . _:genid2 . _:genid3 . _:genid3 . "nca3-epi-co2-r201307" . "Earth Policy Institute Atmospheric Carbon Dioxide Concentration, 1000-2012"^^ . "2013"^^ . "Unknown" . _:genid1 . . "Earth Policy Institute: Data Center - Climate, Energy, and Transportation (http://www.earth-policy.org/data_center/C23)" . "Atmospheric carbon dioxide concentration for the years 1000-2012.\t\t\t\t\t\r\n\r\nSource: Compiled by Earth Policy Institute, with long term historical data from Worldwatch Institute, based on Thomas A. Boden et al., Trends '93: A Compendium of Data on Global Change (Oak Ridge, TN: Oak Ridge National Laboratory, September 1994), and J.T. Houghton et al., eds., Climate Change 1995: The Science of Climate Change, Contribution of Working Group I to the Second Assessment Report of the Intergovernmental Panel on Climate Change (New York: Cambridge University Press, 1996); 1959 to 2012 from National Oceanic and Atmospheric Administration Earth System Research Laboratory, \"Mauna Loa CO2 Annual Mean Data,\" at www.esrl.noaa.gov/gmd/ccgg/trends/co2_data_mlo.html, updated 5 June 2013."^^ . "2013-07-31T00:00:00"^^ . _:genid2 . _:genid3 . "Carbon Dioxide Concentration (ppmv)"^^ . . . _:genid4 . _:genid4 . _:genid4 . _:genid4 .