The challenge to keep global warming below 2 °C

Journal name:
Nature Climate Change
Year published:
Published online

The latest carbon dioxide emissions continue to track the high end of emission scenarios, making it even less likely global warming will stay below 2 °C. A shift to a 2 °C pathway requires immediate significant and sustained global mitigation, with a probable reliance on net negative emissions in the longer term.

At a glance


  1. Estimated CO2 emissions over the past three decades compared with the IS92, SRES and the RCPs.
    Figure 1: Estimated CO2 emissions over the past three decades compared with the IS92, SRES and the RCPs.

    The SA90 data are not shown, but the most relevant (SA90-A) is similar to IS92-A and IS92-F. The uncertainty in historical emissions is ±5% (one standard deviation). Scenario data is generally reported at decadal intervals and we use linear interpolation for intermediate years.

  2. Growth rates of historical and scenario CO2 emissions.
    Figure 2: Growth rates of historical and scenario CO2 emissions.

    The average annual growth rates of the historical emission estimates (black crosses) and the emission scenarios for the time periods of overlaps (shown on the horizontal axis). The growth rates are more comparable for the longer time intervals considered (in order: SA90, 27 years; IS92, 22 years; SRES, 12 years; and RCPs, 7 years). The short-term growth rates of the scenarios do not necessarily reflect the long-term emission pathway (for example, A1B has a high initial growth rate compared with its long-term behaviour and RCP3PD has a higher growth rate until 2010 compared with RCP4.5 and RCP6). For the SRES, we represent the illustrative scenario for each family (filled circles) and each of the contributing model scenarios (open circles). The scenarios generally report emissions at intervals of 10 years or more and we interpolated linearly to 2012; a sensitivity analysis shows a linear interpolation is robust (Supplementary Fig. S14).


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Author information


  1. Center for International Climate and Environmental Research – Oslo (CICERO), PO Box 1128, Blindern 0550, Oslo, Norway

    • Glen P. Peters &
    • Robbie M. Andrew
  2. Carbon Dioxide Information Analysis Center (CDIAC), Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-4842, USA

    • Tom Boden
  3. Global Carbon Project, CSIRO Marine and Atmospheric Research, GPO Box 3023, Canberra, Australia

    • Josep G. Canadell &
    • Michael R. Raupach
  4. Laboratoire des Sciences du Climat et de l'Environnement, CAE – CNRS – UVSQ, 91191 Gif sur Yvette, France

    • Philippe Ciais
  5. Tyndall Centre for Climate Change Research, University of East Anglia, Norwich NR4 7TJ, UK

    • Corinne Le Quéré &
    • Charlie Wilson
  6. Research Institute for Environment, Energy, and Economics, Appalachian State University, ASU Box 32067, Boone, North Carolina 28608-2067, USA

    • Gregg Marland


All authors contributed to the planning of the paper. G.P.P. led the work. G.M. and T.B. contributed the updated CO2 emission data. R.M.A. prepared the figures and associated analysis. G.P.P. did the 2012 emission estimate and the analysis of the historical reduction rates. All authors contributed to data interpretation and to the writing of the paper.

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