PublicationBook Chapter Chapter 3: Energy systems. In Second State of the Carbon Cycle Report (SOCCR2): A Sustained Assessment Report

November 23, 2018
  • Kammen, Daniel
  • Marcotullio, P. J., L. Bruhwiler, S. Davis, J. Engel-Cox, J. Field, C. Gately, K. R. Gurney, D. M. Kammen,
  • E. McGlynn, J. McMahon, W. R. Morrow, III, I. B. Ocko, and R. Torrie, 2018: Chapter 3: Energy systems. In Second State of the Carbon Cycle Report (SOCCR2): A Sustained Assessment Report [Cavallaro, N., G. Shrestha, R. Birdsey, M. A. Mayes, R. G. Najjar, S. C. Reed, P. Romero-Lankao, and Z. Zhu (eds.)]. U.S. Global Change Research Program, Washington, DC, USA, pp. 110-188,
Publication Type:
Book Chapter


  1. In 2013, pri­mary energy use in North Amer­ica exceeded 125 exajoules,1 of which Canada was respon– sible for 11.9%, Mex­ico 6.5%, and the United States 81.6%. Of total pri­mary energy sources, approxi– mately 81% was from fos­sil fuels, which con­tributed to car­bon diox­ide equiv­a­lent (CO2e)2 emis­sions lev– els, 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).
  2. North Amer­i­can energy-​​related CO2e emis­sions have declined at an aver­age rate of about 1% per year, or about 19.4 ter­a­grams CO2e, from 2003 to 2014 (very high confidence).
  3. The shifts in North Amer­i­can energy use and CO2e emis­sions have been dri­ven by fac­tors such
    as 1) lower energy use, ini­tially as a response to the global finan­cial cri­sis of 2007 to 2008 (high con­fi­dence, very likely); but increas­ingly due to 2) greater energy effi­ciency, which has reduced
    the regional energy inten­sity of eco­nomic pro­duc­tion by about 1.5% annu­ally from 2004 to 2013, enabling eco­nomic growth while low­er­ing energy CO2e emis­sions. Energy inten­sity has fallen annu– ally by 1.6% in the United States and 1.5% in Canada (very high con­fi­dence, very likely). Fur­ther fac­tors dri­ving lower car­bon inten­si­ties include 3) increased renew­able energy pro­duc­tion (up 220 peta– joules annu­ally from 2004 to 2013, trans­lat­ing to an 11% annual aver­age increase in renew­ables) (high con­fi­dence, very likely); 4) a shift to nat­ural gas from coal sources for indus­trial and elec­tric­ity pro­duc­tion (high con­fi­dence, likely); and 5) a wide range of new tech­nolo­gies, includ­ing, for exam­ple, alter­na­tive fuel vehi­cles (high con­fi­dence, likely).
  4. A wide range of plau­si­ble futures exists for the North Amer­i­can energy sys­tem in regard to car­bon emis­sions. Fore­casts to 2040, based on cur­rent poli­cies and tech­nolo­gies, sug­gest a range of car­bon emis­sions lev­els from an increase of over 10% to a decrease of over 14% (from 2015 car­bon emis­sions lev­els). Exploratory and back­cast­ing approaches sug­gest that the North Amer­i­can energy sys­tem emis­sions will not decrease by more than 13% (com­pared with 2015 lev­els) with­out both tech­no­log­i­cal advances and changes in pol­icy. For the United States, how­ever, decreases in emis­sions could plau­si­bly meet a national con­tri­bu­tion to a global path­way con­sis­tent with a tar­get of warm­ing to 2°C at a cumu– lative cost of $1 tril­lion to $4 tril­lion (US$ 2005).

Note: Con­fi­dence lev­els are pro­vided as appro­pri­ate for quan­ti­ta­tive, but not qual­i­ta­tive, Key Find­ings and statements.

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 = 1/3.67). See Box P.2, p. 12, in the Pref­ace for more details.


Rec­om­mended Cita­tion for Chapter

Mar­co­tul­lio, P. J., L. Bruh­wiler, S. Davis, J. Engel-​​Cox, J. Field, C. Gately, K. R. Gur­ney, D. M. Kam­men,
E. McG­lynn, J. McMa­hon, W. R. Mor­row, III, I. B. Ocko, and R. Tor­rie, 2018: Chap­ter 3: Energy sys­tems. InSec­ond State of the Car­bon Cycle Report (SOCCR2): A Sus­tained Assess­ment Report [Cav­al­laro, N., G. Shrestha, R. Bird­sey, M. A. Mayes, R. G. Naj­jar, S. C. Reed, P. Romero-​​Lankao, and Z. Zhu (eds.)]. U.S. Global Change Research Pro­gram, Wash­ing­ton, DC, USA, pp. 110–188, https://​doi​.org/​1​0​.​7​9​3​0​/​S​O​C​C​R​2​.​2​0​1​8​.​Ch3.

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