Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Greenhouse-gas emission targets for limiting global warming to 2 °C

Abstract

More than 100 countries have adopted a global warming limit of 2 °C or below (relative to pre-industrial levels) as a guiding principle for mitigation efforts to reduce climate change risks, impacts and damages1,2. However, the greenhouse gas (GHG) emissions corresponding to a specified maximum warming are poorly known owing to uncertainties in the carbon cycle and the climate response. Here we provide a comprehensive probabilistic analysis aimed at quantifying GHG emission budgets for the 2000–50 period that would limit warming throughout the twenty-first century to below 2 °C, based on a combination of published distributions of climate system properties and observational constraints. We show that, for the chosen class of emission scenarios, both cumulative emissions up to 2050 and emission levels in 2050 are robust indicators of the probability that twenty-first century warming will not exceed 2 °C relative to pre-industrial temperatures. Limiting cumulative CO2 emissions over 2000–50 to 1,000 Gt CO2 yields a 25% probability of warming exceeding 2 °C—and a limit of 1,440 Gt CO2 yields a 50% probability—given a representative estimate of the distribution of climate system properties. As known 2000–06 CO2 emissions3 were 234 Gt CO2, less than half the proven economically recoverable oil, gas and coal reserves4,5,6 can still be emitted up to 2050 to achieve such a goal. Recent G8 Communiqués7 envisage halved global GHG emissions by 2050, for which we estimate a 12–45% probability of exceeding 2 °C—assuming 1990 as emission base year and a range of published climate sensitivity distributions. Emissions levels in 2020 are a less robust indicator, but for the scenarios considered, the probability of exceeding 2 °C rises to 53–87% if global GHG emissions are still more than 25% above 2000 levels in 2020.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Joint and marginal probability distributions of climate sensitivity and transient climate response.
Figure 2: Emissions, concentrations and twenty-first century global-mean temperatures.
Figure 3: The probability of exceeding 2 °C warming versus CO 2 emitted in the first half of the twenty-first century.

Similar content being viewed by others

References

  1. Pachauri, R. K. & Reisinger, A. (eds) Climate Change 2007: Synthesis Report (Intergovernmental Panel on Climate Change, Cambridge, UK, 2007)

    Google Scholar 

  2. Council of the European Union. Presidency Conclusions – Brussels, 22/23 March 2005 (European Commission, 2005)

  3. Canadell, J. G. et al. Contributions to accelerating atmospheric CO2 growth from economic activity, carbon intensity, and efficiency of natural sinks. Proc. Natl Acad. Sci. USA 104, 18866–18870 (2007)

    Article  CAS  ADS  Google Scholar 

  4. Clarke, A. W. & Trinnaman, J. A. (eds) 2007 Survey of Energy Resources (World Energy Council, 2007)

    Google Scholar 

  5. Rempe, H., Schmidt, S. & Schwarz-Schampera, U. Reserves, Resources and Availability of Energy Resources 2006 (German Federal Institute for Geosciences and Natural Resources, 2007)

    Google Scholar 

  6. Eggelston, H. S., Buendia, L., Miwa, K., Ngara, T. & Tanabe, K. (eds) 2006 Guidelines for National Greenhouse Gas Inventories (IPCC National Greenhouse Gas Inventories Programme, Hayama, Japan, 2006)

    Google Scholar 

  7. G8. Hokkaido Toyako Summit Leaders Declaration (G8, 2008); available at 〈http://www.mofa.go.jp/policy/economy/summit/2008/doc/doc080714__en.html〉.

  8. Friedlingstein, P. et al. Climate–carbon cycle feedback analysis: Results from the C4MIP model intercomparison. J. Clim. 19, 3337–3353 (2006)

    Article  ADS  Google Scholar 

  9. Brohan, P., Kennedy, J. J., Harris, I., Tett, S. F. B. & Jones, P. D. Uncertainty estimates in regional and global observed temperature changes: A new data set from 1850. J. Geophys. Res. 111 D12106 10.1029/2005JD006548 (2006)

    Article  ADS  Google Scholar 

  10. Domingues, C. M. et al. Improved estimates of upper-ocean warming and multi-decadal sea-level rise. Nature 453, 1090–1093 (2008)

    Article  CAS  ADS  Google Scholar 

  11. Enting, I. G., Wigley, T. M. L. & Heimann, M. Future Emissions and Concentrations of Carbon Dioxide: Key Ocean/Atmosphere/Land Analyses (Research technical paper no. 31, CSIRO Division of Atmospheric Research, 1994)

    Google Scholar 

  12. Wigley, T. M. L., Richels, R. & Edmonds, J. A. Economic and environmental choices in the stabilization of atmospheric CO2 concentrations. Nature 379, 240–243 (1996)

    Article  CAS  ADS  Google Scholar 

  13. Forest, C. E., Stone, P. H., Sokolov, A., Allen, M. R. & Webster, M. D. Quantifying uncertainties in climate system properties with the use of recent climate observations. Science 295, 113–117 (2002)

    Article  CAS  ADS  Google Scholar 

  14. Knutti, R., Stocker, T. F., Joos, F. & Plattner, G. K. Constraints on radiative forcing and future climate change from observations and climate model ensembles. Nature 416, 719–723 (2002)

    Article  CAS  ADS  Google Scholar 

  15. Wigley, T. M. L. & Raper, S. C. B. Interpretation of high projections for global-mean warming. Science 293, 451–454 (2001)

    Article  CAS  ADS  Google Scholar 

  16. Meinshausen, M., Raper, S. C. B. & Wigley, T. M. L. Emulating IPCC AR4 atmosphere-ocean and carbon cycle models for projecting global-mean, hemispheric and land/ocean temperatures: MAGICC 6.0. Atmos. Chem. Phys. Discuss. 8, 6153–6272 (2008)

    Article  ADS  Google Scholar 

  17. Forster, P. et al. in IPCC Climate Change 2007: The Physical Science Basis (eds Solomon, S. et al.) 129–234 (Cambridge Univ. Press, 2007)

    Google Scholar 

  18. Knutti, R. & Hegerl, G. C. The equilibrium sensitivity of the Earth's temperature to radiation changes. Nature Geosci. 1, 735–743 (2008)

    Article  CAS  ADS  Google Scholar 

  19. Frame, D. J., Stone, D. A., Stott, P. A. & Allen, M. R. Alternatives to stabilization scenarios. Geophys. Res. Lett. 33 L14707 10.1029/2006GL025801 (2006)

    Article  ADS  Google Scholar 

  20. Van Vuuren, D. P. et al. Temperature increase of 21st century mitigation scenarios. Proc. Natl Acad. Sci. USA 105, 15258–15262 (2008)

    Article  CAS  ADS  Google Scholar 

  21. Nakicenovic, N. & Swart, R. IPCC Special Report on Emissions Scenarios (Cambridge Univ. Press, 2000)

    Google Scholar 

  22. Solomon, S. et al. (eds) IPCC Climate Change 2007: The Physical Science Basis (Cambridge Univ. Press, 2007)

    Google Scholar 

  23. Metz, B., Davidson, O. R., Bosch, P. R., Dave, R. & Meyer, L. A. (eds) IPCC Climate Change 2007: Mitigation (Cambridge Univ. Press, 2007)

    Google Scholar 

  24. Meinshausen, M. et al. Multi-gas emission pathways to meet climate targets. Clim. Change 75, 151–194 (2006)

    Article  CAS  ADS  Google Scholar 

  25. Schellnhuber, J. S., Cramer, W., Nakicenovic, N., Wigley, T. M. L. & Yohe, G. Avoiding Dangerous Climate Change (Cambridge Univ. Press, 2006)

    Google Scholar 

  26. Meehl, G. A., Covey, C., McAvaney, B., Latif, M. & Stouffer, R. J. Overview of coupled model intercomparison project. Bull. Am. Meteorol. Soc. 86, 89–93 (2005)

    Article  ADS  Google Scholar 

  27. Allen, M. R. et al. Warming caused by cumulative carbon emissions towards the trillionth tonne. Nature 10.1038/nature08019 (this issue)

  28. Houghton, J. T. et al. (eds) IPCC Climate Change 1995: The Science of Climate Change (Cambridge Univ. Press, 1996)

    Google Scholar 

  29. den Elzen, M. G. J. & Meinshausen, M. Meeting the EU 2°C climate target: global and regional emission implications. Clim. Policy 6, 545–564 (2006)

    Article  Google Scholar 

  30. Watkins, K. et al. Fighting Climate Change: Human Solidarity in a Divided World (Human Development Report 2007/2008, Palgrave Macmillan, 2007)

    Google Scholar 

  31. Levitus, S., Antonov, J. & Boyer, T. Warming of the world ocean, 1955-2003. Geophys. Res. Lett. 32 L02604 10.1029/2004GL021592 (2005)

    Article  ADS  Google Scholar 

  32. Knutti, R. & Tomassini, L. Constraints on the transient climate response from observed global temperature and ocean heat uptake. Geophys. Res. Lett. 35 L09701 10.1029/2007GL032904 (2008)

    Article  ADS  Google Scholar 

  33. Knutti, R., Stocker, T. F., Joos, F. & Plattner, G. K. Probabilistic climate change projections using neural networks. Clim. Dyn. 21, 257–272 (2003)

    Article  Google Scholar 

  34. Gregory, J. M., Stouffer, R. J., Raper, S. C. B., Stott, P. A. & Rayner, N. A. An observationally based estimate of the climate sensitivity. J. Clim. 15, 3117–3121 (2002)

    Article  ADS  Google Scholar 

  35. Forest, C. E., Stone, P. H. & Sokolov, A. P. Estimated PDFs of climate system properties including natural and anthropogenic forcings. Geophys. Res. Lett. 33 L01705 10.1029/2005GL023977 (2006)

    Article  ADS  Google Scholar 

  36. Andronova, N. G. & Schlesinger, M. E. Objective estimation of the probability density function for climate sensitivity. J. Geophys. Res. 106, D19 22605–22611 (2001)

    Article  ADS  Google Scholar 

  37. Piani, C., Frame, D. J., Stainforth, D. A. & Allen, M. R. Constraints on climate change from a multi-thousand member ensemble of simulations. Geophys. Res. Lett. 32 L23825 10.1029/2005GL024452 (2005)

    Article  ADS  Google Scholar 

  38. Murphy, J. M. et al. Quantification of modelling uncertainties in a large ensemble of climate change simulations. Nature 430, 768–772 (2004)

    Article  CAS  ADS  Google Scholar 

  39. Annan, J. D. & Hargreaves, J. C. Using multiple observationally-based constraints to estimate climate sensitivity. Geophys. Res. Lett. 33 L06704 10.1029/2005GL025259 (2006)

    Article  ADS  Google Scholar 

  40. Hegerl, G. C., Crowley, T. J., Hyde, W. T. & Frame, D. J. Climate sensitivity constrained by temperature reconstructions over the past seven centuries. Nature 440, 1029–1032 (2006)

    Article  CAS  ADS  Google Scholar 

  41. Knutti, R., Meehl, G. A., Allen, M. R. & Stainforth, D. A. Constraining climate sensitivity from the seasonal cycle in surface temperature. J. Clim. 19, 4224–4233 (2006)

    Article  ADS  Google Scholar 

  42. Clarke, A. W. & Trinnaman, J. A. (eds) Survey of Energy Resources 2007 (World Energy Council, 2007)

    Google Scholar 

  43. BP. BP Statistical Review of World Energy June 2008 (BP, London, 2008); available at 〈http://www.bp.com/statisticalreview〉.

  44. Rempe, H., Schmidt, S. & Schwarz-Schampera, U. Reserves, Resources and Availability of Energy Resources 2006 (German Federal Institute for Geosciences and Natural Resources, 2007)

    Google Scholar 

  45. Abraham, K. International outlook: world trends: Operators ride the crest of the global wave. World Oil 228, no. 9 (2007)

  46. Radler, M. Special report: Oil production, reserves increase slightly in 2006. Oil Gas J. 104, 20–23 (2006); available at 〈http://www.ogj.com/currentissue/index.cfm?p = 7&v = 104&i = 47〉

    Google Scholar 

Download references

Acknowledgements

We thank T. Wigley, M. Schaeffer, K. Briffa, R. Schofield, T. S., von Deimling, J. Nabel, J. Rogelj, V. Huber and A. Fischlin for discussions and comments on earlier manuscripts and our code, J. Gregory for AOGCM diagnostics, D. Giebitz-Rheinbay and B. Kriemann for IT support and the EMF-21 modelling groups for providing their emission scenarios. M.M. thanks DAAD and the German Ministry of Environment for financial support. We acknowledge the modelling groups, the Program for Climate Model Diagnosis and Intercomparison (PCMDI) and the WCRP's Working Group on Coupled Modelling (WGCM) for their roles in making available the WCRP CMIP3 multi-model data set. Support of this data set is provided by the Office of Science, US Department of Energy.

Author Contributions M.M. and N.M. designed the research with input from W.H., R.K. and M.A. M.M. performed the climate modelling, N.M. the statistical analysis, W.H. the compilation of fossil fuel reserve estimates; all authors contributed to writing the paper.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Malte Meinshausen.

Additional information

Accompanying datasets are available at http://www.primap.org.

Supplementary information

Supplementary Information

This file contains Supplementary Data, Supplementary Figures S1-S6 with Legends, Supplementary Tables S1-S4 and Supplementary References. (PDF 10562 kb)

Supplementary Data

This file contains a 2C Check Tool Table for Emission Pathway Characteristics together with the background calculations. (XLS 4639 kb)

Supplementary Data

The attached source code files contain the statistical routines to constrain the parameter space of the carbon cycle climate model MAGICC6, as used within the study Meinshausen et al. (2009) "Greenhouse gas emission targets for limiting global warming to 2∞C." Nature. (ZIP 19 kb)

Please see http://www.primap.org for the complete set of EQW emission pathways that have been used in this study.

PowerPoint slides

Rights and permissions

Reprints and permissions

About this article

Cite this article

Meinshausen, M., Meinshausen, N., Hare, W. et al. Greenhouse-gas emission targets for limiting global warming to 2 °C. Nature 458, 1158–1162 (2009). https://doi.org/10.1038/nature08017

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature08017

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing