Letter | Published:

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

Nature volume 458, pages 11581162 (30 April 2009) | Download Citation

Subjects

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.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1.

    & (eds) Climate Change 2007: Synthesis Report (Intergovernmental Panel on Climate Change, Cambridge, UK, 2007)

  2. 2.

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

  3. 3.

    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)

  4. 4.

    & (eds) 2007 Survey of Energy Resources (World Energy Council, 2007)

  5. 5.

    , & Reserves, Resources and Availability of Energy Resources 2006 (German Federal Institute for Geosciences and Natural Resources, 2007)

  6. 6.

    , , , & (eds) 2006 Guidelines for National Greenhouse Gas Inventories (IPCC National Greenhouse Gas Inventories Programme, Hayama, Japan, 2006)

  7. 7.

    G8. Hokkaido Toyako Summit Leaders Declaration (G8, 2008); available at 〈〉.

  8. 8.

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

  9. 9.

    , , , & Uncertainty estimates in regional and global observed temperature changes: A new data set from 1850. J. Geophys. Res. 111 D12106 10.1029/2005JD006548 (2006)

  10. 10.

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

  11. 11.

    , & Future Emissions and Concentrations of Carbon Dioxide: Key Ocean/Atmosphere/Land Analyses (Research technical paper no. 31, CSIRO Division of Atmospheric Research, 1994)

  12. 12.

    , & Economic and environmental choices in the stabilization of atmospheric CO2 concentrations. Nature 379, 240–243 (1996)

  13. 13.

    , , , & Quantifying uncertainties in climate system properties with the use of recent climate observations. Science 295, 113–117 (2002)

  14. 14.

    , , & Constraints on radiative forcing and future climate change from observations and climate model ensembles. Nature 416, 719–723 (2002)

  15. 15.

    & Interpretation of high projections for global-mean warming. Science 293, 451–454 (2001)

  16. 16.

    , & 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)

  17. 17.

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

  18. 18.

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

  19. 19.

    , , & Alternatives to stabilization scenarios. Geophys. Res. Lett. 33 L14707 10.1029/2006GL025801 (2006)

  20. 20.

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

  21. 21.

    & IPCC Special Report on Emissions Scenarios (Cambridge Univ. Press, 2000)

  22. 22.

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

  23. 23.

    , , , & (eds) IPCC Climate Change 2007: Mitigation (Cambridge Univ. Press, 2007)

  24. 24.

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

  25. 25.

    , , , & Avoiding Dangerous Climate Change (Cambridge Univ. Press, 2006)

  26. 26.

    , , , & Overview of coupled model intercomparison project. Bull. Am. Meteorol. Soc. 86, 89–93 (2005)

  27. 27.

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

  28. 28.

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

  29. 29.

    & Meeting the EU 2°C climate target: global and regional emission implications. Clim. Policy 6, 545–564 (2006)

  30. 30.

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

  31. 31.

    , & Warming of the world ocean, 1955-2003. Geophys. Res. Lett. 32 L02604 10.1029/2004GL021592 (2005)

  32. 32.

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

  33. 33.

    , , & Probabilistic climate change projections using neural networks. Clim. Dyn. 21, 257–272 (2003)

  34. 34.

    , , , & An observationally based estimate of the climate sensitivity. J. Clim. 15, 3117–3121 (2002)

  35. 35.

    , & Estimated PDFs of climate system properties including natural and anthropogenic forcings. Geophys. Res. Lett. 33 L01705 10.1029/2005GL023977 (2006)

  36. 36.

    & Objective estimation of the probability density function for climate sensitivity. J. Geophys. Res. 106, D19 22605–22611 (2001)

  37. 37.

    , , & Constraints on climate change from a multi-thousand member ensemble of simulations. Geophys. Res. Lett. 32 L23825 10.1029/2005GL024452 (2005)

  38. 38.

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

  39. 39.

    & Using multiple observationally-based constraints to estimate climate sensitivity. Geophys. Res. Lett. 33 L06704 10.1029/2005GL025259 (2006)

  40. 40.

    , , & Climate sensitivity constrained by temperature reconstructions over the past seven centuries. Nature 440, 1029–1032 (2006)

  41. 41.

    , , & Constraining climate sensitivity from the seasonal cycle in surface temperature. J. Clim. 19, 4224–4233 (2006)

  42. 42.

    & (eds) Survey of Energy Resources 2007 (World Energy Council, 2007)

  43. 43.

    BP. BP Statistical Review of World Energy June 2008 (BP, London, 2008); available at 〈〉.

  44. 44.

    , & Reserves, Resources and Availability of Energy Resources 2006 (German Federal Institute for Geosciences and Natural Resources, 2007)

  45. 45.

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

  46. 46.

    Special report: Oil production, reserves increase slightly in 2006. Oil Gas J. 104, 20–23 (2006); available at 〈p = 7&v = 104&i = 47〉

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

Affiliations

  1. Potsdam Institute for Climate Impact Research, Telegraphenberg, 14412 Potsdam, Germany

    • Malte Meinshausen
    • , William Hare
    •  & Katja Frieler
  2. Department of Statistics, University of Oxford, South Parks Road, Oxford OX1 3TG, UK

    • Nicolai Meinshausen
  3. Climate Analytics, Telegraphenberg, 14412 Potsdam, Germany

    • William Hare
  4. Centre for Air Transport and the Environment, Manchester Metropolitan University, Chester Street, Manchester M1 5GD, UK

    • Sarah C. B. Raper
  5. Institute for Atmospheric and Climate Science, ETH Zurich, 8092 Zurich, Switzerland

    • Reto Knutti
  6. Smith School of Enterprise and the Environment, University of Oxford, Oxford OX1 2BQ, UK

    • David J. Frame
  7. Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK

    • David J. Frame
    •  & Myles R. Allen

Authors

  1. Search for Malte Meinshausen in:

  2. Search for Nicolai Meinshausen in:

  3. Search for William Hare in:

  4. Search for Sarah C. B. Raper in:

  5. Search for Katja Frieler in:

  6. Search for Reto Knutti in:

  7. Search for David J. Frame in:

  8. Search for Myles R. Allen in:

Corresponding author

Correspondence to Malte Meinshausen.

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

Supplementary information

PDF files

  1. 1.

    Supplementary Information

    This file contains Supplementary Data, Supplementary Figures S1-S6 with Legends, Supplementary Tables S1-S4 and Supplementary References.

Excel files

  1. 1.

    Supplementary Data

    This file contains a 2C Check Tool Table for Emission Pathway Characteristics together with the background calculations.

Zip files

  1. 1.

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

About this article

Publication history

Received

Accepted

Published

DOI

https://doi.org/10.1038/nature08017

Further reading

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.