finding 3.1 : key-message-3-1

In 2013, primary energy use in North America exceeded 125 exajoules (1), of which Canada was responsible for 11.9%, Mexico 6.5%, and the United States 81.6%. Of total primary energy sources, approximately 81% was from fossil fuels, which contributed to carbon dioxide equivalent (CO2e) (2) emissions levels, exceeding 1.76 petagrams of carbon, or about 20% of the global total for energy-related activities. Of these emissions, coal accounted for 28%, oil 44%, and natural gas 28% (very high confidence, likely).

(1) One exajoule is equal to one quintillion (1018) joules, a derived unit of energy in the International System of Units.
(2) Carbon dioxide equivalent (CO2e): Amount of CO2 that would produce the same effect on the radiative balance of Earth’s climate system as another greenhouse gas, such as methane (CH4) or nitrous oxide (N2O), on a 100-year timescale. For comparison to units of carbon, each kg CO2e is equivalent to 0.273 kg C (0.273 = 13.67). See Box P.2 in the Preface for more details.

This finding is from chapter 3 of Second State of the Carbon Cycle Report (SOCCR2): A Sustained Assessment Report.

Description of evidence base: Data on energy use are collected by the U.S. Department of Energy’s (U.S. DOE) Energy Information Administration (EIA) and the Organisation for Economic Cooperation and Development’s (OECD) International Energy Agency (IEA). Data for CO2e were accessed from a number of sources, including the EIA, IEA, U.S. DOE Carbon Dioxide Information Analysis Center (CDIAC) database (Boden et al., 2016), and the World Resources Institute (WRI) CAIT database ( All data suggest similar trends, although the exact values differ.

New information and remaining uncertainties: These datasets include uncertainties related to the amount of fossil fuel used (i.e., typically identified through sales-weighted averages to create a national average) and the carbon and heat contents of the energy reserve (e.g., U.S. EPA 2017a). According to the literature, there are further uncertainties related to lost and fugitive emissions (Alvarez et al., 2012; Brandt et al., 2014; Karion et al., 2013; Pétron et al., 2014; Zavala-Araiza et al., 2015). Estimates of fugitive methane (CH4) levels indicate that these emissions are unlikely to substantially alter Key Finding 1 (Alvarez et al., 2012; Brandt et al., 2014). Fugitive CH4 from oil, gas, and coal production and transportation is included in the U.S. Environmental Protection Agency (U.S. EPA), U.S. DOE, Canadian, and Mexican inventories, but there may be further emissions not yet accounted. Furthermore, while the trends are consistent across data sources, the absolute values of greenhouse gas (GHG) emissions levels from energy consumption and production vary across datasets because of differences in system boundary definitions, inclusion of industrial process emissions, emissions factors applied, and other issues.

Assessment of confidence based on evidence: There is very high confidence in the likelihood that the statement is based on consistent findings across the literature.

This finding was derived from figure P.2: P.2. Likelihood and Confidence Evaluation

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