Letter | Published:

Sensitivity of tropical carbon to climate change constrained by carbon dioxide variability

Nature volume 494, pages 341344 (21 February 2013) | Download Citation

Abstract

The release of carbon from tropical forests may exacerbate future climate change1, but the magnitude of the effect in climate models remains uncertain2. Coupled climate–carbon-cycle models generally agree that carbon storage on land will increase as a result of the simultaneous enhancement of plant photosynthesis and water use efficiency under higher atmospheric CO2 concentrations, but will decrease owing to higher soil and plant respiration rates associated with warming temperatures3. At present, the balance between these effects varies markedly among coupled climate–carbon-cycle models, leading to a range of 330 gigatonnes in the projected change in the amount of carbon stored on tropical land by 2100. Explanations for this large uncertainty include differences in the predicted change in rainfall in Amazonia4,5 and variations in the responses of alternative vegetation models to warming6. Here we identify an emergent linear relationship, across an ensemble of models7, between the sensitivity of tropical land carbon storage to warming and the sensitivity of the annual growth rate of atmospheric CO2 to tropical temperature anomalies8. Combined with contemporary observations of atmospheric CO2 concentration and tropical temperature, this relationship provides a tight constraint on the sensitivity of tropical land carbon to climate change. We estimate that over tropical land from latitude 30° north to 30° south, warming alone will release 53 ± 17 gigatonnes of carbon per kelvin. Compared with the unconstrained ensemble of climate–carbon-cycle projections, this indicates a much lower risk of Amazon forest dieback under CO2-induced climate change if CO2 fertilization effects are as large as suggested by current models9. Our study, however, also implies greater certainty that carbon will be lost from tropical land if warming arises from reductions in aerosols10 or increases in other greenhouse gases11.

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References

  1. 1.

    , , , & Acceleration of global warming due to carbon cycle feedbacks in a coupled climate model. Nature 408, 184–187 (2000)

  2. 2.

    et al. Climate change, deforestation, and the fate of the Amazon. Science 319, 169–172 (2008)

  3. 3.

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

  4. 4.

    et al. Development of probability density functions for future South American rainfall. New Phytol. 187, 682–693 (2010)

  5. 5.

    et al. Estimating the risk of Amazonian forest dieback. New Phytol. 187, 694–706 (2010)

  6. 6.

    et al. Multiple mechanisms of Amazonian forest biomass losses in three dynamic global vegetation models under climate change. New Phytol. 187, 647–665 (2010)

  7. 7.

    & Using the current seasonal cycle to constrain snow albedo feedback in future climate change. Geophys. Res. Lett. 33, L03502 (2006)

  8. 8.

    Modulation of atmospheric carbon dioxide by the Southern Oscillation. Nature 261, 116–118 (1976)

  9. 9.

    et al. Amazon dieback under climate-carbon cycle projections for the 21st century. Theor. Appl. Climatol. 78, 137–156 (2004)

  10. 10.

    et al. Increasing risk of Amazonian drought due to decreasing aerosol pollution. Nature 453, 212–215 (2008)

  11. 11.

    et al. Highly contrasting effects of different climate forcing agents on ecosystem services. Phil. Trans. R. Soc. A 369, 2026–2037 (2011)

  12. 12.

    et al. Emissions Scenarios: Summary for Policymakers. Spec. Report (Intergovernmental Panel on Climate Change, 2000)

  13. 13.

    , , & How positive is the feedback between climate change and the carbon cycle? Tellus 55B, 692–700 (2003)

  14. 14.

    et al. High sensitivity of future global warming to land carbon cycle processes. Environ. Res. Lett. 7, 024002 (2012)

  15. 15.

    et al. The next generation of scenarios for climate change research and assessment. Nature 463, 747–756 (2010)

  16. 16.

    et al. Nitrogen and climate change. Science 302, 1512–1513 (2003)

  17. 17.

    , & Terrestrial nitrogen feedbacks may accelerate future climate change. Geophys. Res. Lett. 37, L01401 (2010)

  18. 18.

    et al. Increasing biomass in Amazonian forest plots. Phil. Trans. R. Soc. Lond. B 359, 353–365 (2004)

  19. 19.

    et al. Increasing carbon storage in intact African tropical forests. Nature 457, 1003–1006 (2009)

  20. 20.

    et al. The drought of Amazonia in 2005. J. Clim. 21, 495–516 (2008)

  21. 21.

    et al. The drought of 2010 in the context of historical droughts in the Amazon region. Geophys. Res. Lett. 38, L12703 (2011)

  22. 22.

    et al. Drought sensitivity of the Amazon rainforest. Science 323, 1344–1347 (2009)

  23. 23.

    et al. Tipping elements in the Earth’s climate system. Proc. Natl Acad. Sci. USA 105, 1786–1793 (2008)

  24. 24.

    & On the significance of atmospheric CO2 growth rate anomalies in 2002–2003. Geophys. Res. Lett. 32, L14816 (2005)

  25. 25.

    et al. in Climate Change 2007: The Physical Science Basis (eds et al.) 499–587 (Cambridge Univ. Press, 2007)

  26. 26.

    & Extension and integration of atmospheric carbon dioxide data into a globally consistent measurement record. J. Geophys. Res. 100, 11593–11610 (1995)

  27. 27.

    et al. The RCP greenhouse gas concentrations and their extensions from 1765 to 2500. Clim. Change 109, 213–241 (2011)

  28. 28.

    et al. Improvements to NOAA’s historical merged land-ocean surface temperature analysis (1880–2006). J. Clim. 21, 2283–2296 (2008)

  29. 29.

    et al. Impact of changes in diffuse radiation on the global land carbon sink. Nature 458, 1014–1017 (2009)

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Acknowledgements

We acknowledge funding from the NERC NCEO programme (P.M.C. and C.M.L.); the EU Greencycles II project (P.M.C. and P.F.); the EU FP7 ‘CARBONES’ project (D.P. and C.D.J.); the Joint DECC/Defra Met Office Hadley Centre Climate Programme (GA01101) (D.P., B.B.B. and C.D.J.); the CEH Science Budget (C.H.) and the Newton Institute programme on ‘Mathematical and Statistical Approaches to Climate Modelling and Prediction’, during which this research was first formulated (P.M.C., B.B.B. and C.H.). We also acknowledge the modelling groups that provided results to C4MIP.

Author information

Affiliations

  1. College of Engineering, Mathematics and Physical Science, University of Exeter, Exeter EX4 4QF, UK

    • Peter M. Cox
    • , Pierre Friedlingstein
    •  & Catherine M. Luke
  2. Hadley Centre, Met Office, Exeter EX1 3PB, UK

    • David Pearson
    • , Ben B. Booth
    •  & Chris D. Jones
  3. Centre for Ecology and Hydrology, Wallingford OX10 8BB, UK

    • Chris Huntingford

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Contributions

P.M.C. led the study and drafted the manuscript. D.P. assisted with the statistical analysis, especially the estimation of the observationally constrained PDF in Fig. 3b. P.F. provided data and guidance on the C4MIP model ensemble, and B.B.B. did likewise for the HadCM3 carbon-cycle ensemble. C.H. processed observational climate data sets to produce time series of tropical mean temperature anomalies. P.M.C., C.D.J., P.F. and C.H. have had discussions over many years concerning the relationship between the interannual variability and the long-term sensitivity of the land carbon cycle to climate change. C.M.L. provided invaluable insights into the interpretation of the regression line in Fig. 3a. All co-authors commented on and provided edits to the original manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Peter M. Cox.

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    Supplementary Information

    This file contains Supplementary Table 1 and Supplementary Figures 1-3.

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https://doi.org/10.1038/nature11882

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