Skip to main content

Thank you for visiting 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.

  • Letter
  • Published:

Detection of a direct carbon dioxide effect in continental river runoff records


Continental runoff has increased through the twentieth century1,2 despite more intensive human water consumption3. Possible reasons for the increase include: climate change and variability, deforestation, solar dimming4, and direct atmospheric carbon dioxide (CO2) effects on plant transpiration5. All of these mechanisms have the potential to affect precipitation and/or evaporation and thereby modify runoff. Here we use a mechanistic land-surface model6 and optimal fingerprinting statistical techniques7 to attribute observational runoff changes1 into contributions due to these factors. The model successfully captures the climate-driven inter-annual runoff variability, but twentieth-century climate alone is insufficient to explain the runoff trends. Instead we find that the trends are consistent with a suppression of plant transpiration due to CO2-induced stomatal closure. This result will affect projections of freshwater availability, and also represents the detection of a direct CO2 effect on the functioning of the terrestrial biosphere.

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

Access options

Buy this article

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

Figure 1: Trends in continental water budgets.
Figure 2: β scale factors obtained from the optimal fingerprinting technique.
Figure 3: Attribution of post-1960 overall runoff trend.

Similar content being viewed by others


  1. Labat, D., Godderis, Y., Probst, J. L. & Guyot, J. L. Evidence for global runoff increase related to climate warming. Adv. Water Res. 27, 631–642 (2004)

    Article  Google Scholar 

  2. Probst, J. L. & Tardy, Y. Long range stream-flow and world continental runoff fluctuations since the beginning of this century. J. Hydrol. 94, 289–311 (1987)

    Article  ADS  Google Scholar 

  3. Shiklomanov, I. A. Appraisal and assessment of world water resources. Water Int. 25, 11–32 (2000)

    Article  Google Scholar 

  4. Stanhill, G. & Cohen, S. Global dimming: a review of the evidence for a widespread and significant reduction in global radiation with discussion of its probable causes and possible agricultural consequences. Agric. For. Met. 107, 255–278 (2001)

    Article  Google Scholar 

  5. Field, C., Jackson, R. & Mooney, H. Stomatal responses to increased CO2: implications from the plant to the global-scale. Plant Cell Environ. 18, 1214–1255 (1995)

    Article  Google Scholar 

  6. Essery, R. L. H., Best, M. J., Betts, R. A., Cox, P. M. & Taylor, C. M. Explicit representation of sub-grid heterogeneity in a GCM land surface scheme. J. Hydromet. 4, 530–543 (2003)

    Article  Google Scholar 

  7. Tett, S. F. B. et al. Estimation of natural and anthropogenic contributions to 20th century temperature change. J. Geophys. Res. 107, 4306, doi:10.1029/2000JD000028 (2002)

    Article  Google Scholar 

  8. Roderick, G. D. & Farquhar, G. D. The cause of decreased pan evaporation over the last 50 years. Science 298, 1410–1411 (2002)

    ADS  CAS  PubMed  Google Scholar 

  9. New, M., Hulme, M. & Jones, P. Representing twentieth-century space-time climate variability. Part II: Development of 1901–96 monthly grids of terrestrial surface climate. J. Clim. 13, 2217–2238 (2000)

    Article  ADS  Google Scholar 

  10. Cox, P. M., Huntingford, C. & Harding, R. J. A canopy conductance and photosynthesis model for use in a GCM land surface scheme. J. Hydrol. 213, 79–94 (1998)

    Article  Google Scholar 

  11. Harding, R. J., Huntingford, C. & Cox, P. M. Modelling long-term transpiration measurments from grassland in southern England. Agric. For. Met. 100, 309–322 (2000)

    Article  Google Scholar 

  12. Pope, V. D., Gallani, M. L., Rowntree, P. R. & Stratton, R. A. The impact of new physical parametrizations in the Hadley Centre climate model: HadAM3. Clim. Dyn. 16, 123–146 (2000)

    Article  Google Scholar 

  13. Stott, P. A. et al. HadGEM1—Transient simulations with HadGEM1 using historic and SRES scenarios. J. Clim.(in the press)

  14. Goldewijk, K. K. Estimating global land use change over the past 300 years: the HYDE database. Glob. Biogeochem. Cycles 15, 417–433 (2001)

    Article  ADS  Google Scholar 

  15. Mitchell, J. F. B. & Karoly, D. J. in Climate Change 2001. Impacts: The Scientific Basis (eds Houghton, J. T. et al.) 697–738 (Cambridge Univ. Press, Cambridge, 2001)

    Google Scholar 

  16. Lambert, F. H., Stott, P. A., Allen, M. R. & Palmer, M. A. Detection and attribution of changes in 20th century land precipitation. Geophys. Res. Lett. 31, L10203, doi:10.1029/2005GL023654 (2004)

    Article  ADS  Google Scholar 

  17. Boucher, O., Myhre, G. & Myhre, A. Direct human influence of irrigation on atmospheric water vapour and climate. Clim. Dyn. 22, 597–603 (2004)

    Article  Google Scholar 

  18. FAOSTAT Statistical Databases: Land Use. (Food and Agriculture Organisation of the United Nations, July 2005).

  19. FAOSTAT Statistical Databases: Population. (Food and Agriculture Organisation of the United Nations, July 2005).

  20. Loveland, T. R. et al. Development of a global land cover characteristics database and IGBP DISCover from 1-km AVHRR data. Int. J. Remote Sens. 21, 1303–1330 (2000)

    Article  Google Scholar 

  21. McNaughton, K. G. & Jarvis, P. G. Effects of spatial scale on stomatal control of transpiration. Agric. For. Met. 54, 279–302 (1991)

    Article  Google Scholar 

  22. Betts, R. A., Cox, P. M., Lee, S. E. & Woodward, F. I. Contrasting physiological and structural vegetation feedbacks in climate change simulations. Nature 387, 796–799 (1997)

    Article  ADS  CAS  Google Scholar 

  23. Arnell, N. & Lui, C. in Climate Change 2001. Impacts: Adaptation and Vulnerability (eds McCarthy, J. J. et al.) 191–234 (Cambridge Univ. Press, Cambridge, 2001)

    Google Scholar 

  24. Sellers, P. J. et al. Comparison of radiative and physiological effects of doubled atmospheric CO2 on climate. Science 271, 1402–1406 (1996)

    Article  ADS  CAS  Google Scholar 

  25. Cox, P. M. et al. The impact of new land surface physics on the GCM simulation of climate and climate sensitivity. Clim. Dyn. 15, 183–203 (1999)

    Article  Google Scholar 

  26. Gordon, C. et al. The simulation of SST, sea ice extents and ocean heat transports in a version of the Hadley Centre coupled model without flux adjustments. Clim. Dyn. 16, 147–168 (2000)

    Article  Google Scholar 

  27. Henning, D. in Atlas of the Surface Heat Balance of the Continents 6–9 (Gebruder Borntraeger, Berlin, 1989)

    Google Scholar 

  28. Zhao, M. & Dirmeyer, P. Production and analysis of GSWP2 near-surface meteorology data sets. COLA Technic. Rep. 159, 1–36 (2003)

    Google Scholar 

  29. Liepert, B. G. Observed reductions of surface solar radiation at sites in the United States and worldwide from 1961 to 1990. Geophys. Res. Lett. 29, 1421, doi:10.1029/2002GL014910 (2002)

    Article  ADS  Google Scholar 

  30. Fekete, B. M., Vorosmarty, C. J. & Grabs, W. High-resolution fields of global runoff combining observed river discharge and simulated water balances. Glob. Biogechem. Cycles 16, 1042, doi:10.1029/1999GB001254 (2002)

    ADS  Google Scholar 

Download references


We thank D. Labat (Laboratoire de Mécanisme de Transferts en Géologie, UMR CNRS, Toulouse, France) for providing the observational runoff data. We thank D. Sexton for statistical advice and A. Jones for discussions. N.G., R.A.B., O.B. and P.A.S. were supported by the UK Department for Environment, Food and Rural Affairs, and P.M.C. and C.H. by the UK Natural Environment Research Council.

Author information

Authors and Affiliations


Corresponding author

Correspondence to N. Gedney.

Ethics declarations

Competing interests

Reprints and permissions information is available at The authors declare no competing financial interests.

Supplementary information

Supplementary Figure 1

Time series of the annual mean anomalies of continental runoff. The observational data (black) and the best fit from the optimal finger-printing technique (red) are shown. (PDF 33 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Gedney, N., Cox, P., Betts, R. et al. Detection of a direct carbon dioxide effect in continental river runoff records. Nature 439, 835–838 (2006).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


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.


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