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.

Reduction in carbon uptake during turn of the century drought in western North America


Fossil fuel emissions aside, temperate North America is a net sink of carbon dioxide at present1,2,3. Year-to-year variations in this carbon sink are linked to variations in hydroclimate that affect net ecosystem productivity3,4. The severity and incidence of climatic extremes, including drought, have increased as a result of climate warming5,6,7,8. Here, we examine the effect of the turn of the century drought in western North America on carbon uptake in the region, using reanalysis data, remote sensing observations and data from global monitoring networks. We show that the area-integrated strength of the western North American carbon sink declined by 30–298 Tg C yr−1 during the 2000–2004 drought. We further document a pronounced drying of the terrestrial biosphere during this period, together with a reduction in river discharge and a loss of cropland productivity. We compare our findings with previous palaeoclimate reconstructions7 and show that the last drought of this magnitude occurred more than 800 years ago. Based on projected changes in precipitation and drought severity, we estimate that the present mid-latitude carbon sink of 177–623 Tg C yr−1 in western North America could disappear by the end of the century.

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

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: FLUXNET sites and enviroclimatic indicators.
Figure 2: Basin runoff and crop productivity in the western conterminous United States from 1997 to 2007.
Figure 3: Carbon and energy fluxes observed at FLUXNET from 1997 to 2007.
Figure 4: Drought over western North America from 800 to 2100.


  1. Nemani, R. R. et al. Recent trends in hydrological balance have enhanced the terrestrial carbon sink in the United States. Geophys. Res. Lett. 29, 1468 (2002).

    Article  Google Scholar 

  2. Potter, C. S. et al. Estimating carbon budgets for US ecosystems. Eos 87, 85–96 (2006).

    Article  Google Scholar 

  3. Xiao, J. et al. Assessing net ecosystem carbon exchange of US terrestrial ecosystems by integrating eddy covariance flux measurements and satellite observations. Agric. For. Meteorol. 151, 60–69 (2011).

    Article  Google Scholar 

  4. Schwalm, C. R., Williams, C. A. & Schaefer, K. M. Carbon consequences of global hydrologic change, 1948–2009. J. Geophys. Res. 116, G03042 (2011).

    Article  Google Scholar 

  5. Bates, B. C., Kundzewicz, Z. W., Wu, S. & Palutikof, J. P. (eds) Climate Change and Water. Technical Paper of the Intergovernmental Panel on Climate Change (IPCC Secretariat, 2008).

  6. Huntington, T. G. Evidence for intensification of the global water cycle: Review and synthesis. J. Hydrol. 319, 83–95 (2006).

    Article  Google Scholar 

  7. Cook, E. R., Woodhouse, C. A., Eakin, C. M., Meko, D. M. & Stahle, D. W. Long term aridity changes in the western United States. Science 306, 1015–1018 (2004).

    Article  Google Scholar 

  8. Dai, A., Trenberth, K. E. & Qian, T. A global data set of Palmer Drought Severity Index for 1870–2002: Relationship with soil moisture and effects of surface warming. J. Hydrometerol. 5, 1117–1130 (2004).

    Article  Google Scholar 

  9. Lobell, D. B. et al. Satellite estimates of productivity and light use efficiency in United States agriculture, 1982–1998. Glob. Change Biol. 8, 1–15 (2002).

    Article  Google Scholar 

  10. Misson, L., Tang, J., Xu, M., McKay, M. & Goldstein, A. Influences of recovery from clear-cut, climate variability, and thinning on the carbon balance of a young ponderosa pine plantation. Agric. For. Meteorol. 130, 207–222 (2005).

    Article  Google Scholar 

  11. Breshears, D. D., López-Hoffman, L. & Graumlich, L. J. When ecosystem services crash: preparing for big, fast, patchy climate change. Ambio 40, 256–263 (2011).

    Article  Google Scholar 

  12. Schwalm, C. R. et al. Assimilation exceeds respiration sensitivity to drought: A FLUXNET synthesis. Glob. Change Biol. 16, 657–670 (2010).

    Article  Google Scholar 

  13. Hibbard, K. A., Law, B. E., Reichstein, M. & Sulzman, J. An analysis of soil respiration across northern hemisphere temperate ecosystems. Biogeochemistry 73, 29–70 (2005).

    Article  Google Scholar 

  14. Scott, R. L., Huxman, T. E., Williams, D. & Goodrich, D. C. Ecohydrological impacts of woody-plant encroachment: Seasonal patterns of water and carbon dioxide exchange within a semiarid riparian environment. Glob. Change Biol. 12, 311–324 (2006).

    Article  Google Scholar 

  15. Wang, S. & Davidson, A. Impact of climate variations on surface albedo of a temperate grassland. Agr. Forest Meteorol. 142, 133–142 (2007).

    Article  Google Scholar 

  16. Alley, W. M. Palmer drought severity index: Limitations and assumptions. J. Clim. Appl. Meteorol. 23, 1100–1109 (1984).

    Article  Google Scholar 

  17. Cook, E. R. et al. Megadroughts in North America: placing IPCC projections of hydroclimatic change in a long-term palaeoclimate context. J. Quat. Sci. 25, 48–61 (2010).

    Article  Google Scholar 

  18. Woodhouse, C. A., Meko, D. M., MacDonald, G. M., Stahle, D. W. & Cook, E. R. A 1,200-year perspective of 21st century drought in southwestern North America. Proc. Natl Acad. Sci. USA 107, 21283–21288 (2010).

    Article  Google Scholar 

  19. Stahle, D. W., Fye, F. K., Cook, E. R. & Griffin, R. D. Tree-ring reconstructed megadroughts over North America since AD 1300. Climatic Change 83, 133–149 (2007).

    Article  Google Scholar 

  20. Mote, P. W., Hamlet, A. F., Clark, M. P. & Lettenmaier, D. P. Declining mountain snowpack in western North America. Bull. Am. Meteorol. Soc. 86, 39–49 (2005).

    Article  Google Scholar 

  21. Pederson, G. T. et al. The unusual nature of recent snowpack declines in the North American Cordillera. Science 333, 332–335 (2011).

    Article  Google Scholar 

  22. Seager, R. et al. Model projections of an imminent transition to a more arid climate in southwestern North America. Science 316, 1181–1184 (2007).

    Article  Google Scholar 

  23. Burke, E. J., Brown, S. J. & Christidis, N. Modeling the recent evolution of global drought and projections for the twenty-first century with the Hadley centre climate model. J. Hydrometeorol. 7, 1113–1125 (2006).

    Article  Google Scholar 

  24. Wehner, M. F. et al. Projections of future drought in the Continental United States and Mexico. J. Hydrometeorol. 12, 1359–1377 (2011).

    Article  Google Scholar 

  25. Meehl, G. A. et al. The WCRP CMIP3 multi-model dataset: A new era in climate change research. Bull. Amer. Meteorol. Soc. 88, 1383–1394 (2007).

    Article  Google Scholar 

  26. Zhao, M. & Running, S. W. Drought-Induced reduction in global terrestrial net primary production from 2000 through 2009. Science 329, 940–943 (2010).

    Article  Google Scholar 

  27. Bosilovich, M., Chen, J., Robertson, F. R. & Adler, Evaluation of global precipitation in reanalyses. J. Appl. Meteorol. Climatol. 47, 2279–2299 (2008).

    Article  Google Scholar 

  28. Hicke, J. A., Lobell, D. B. & Asner, G. P. Cropland area and net primary production computed from 30 Years of USDA agricultural harvest data. Earth Interact. 8, 1–20 (2004).

    Article  Google Scholar 

  29. Jung, M. et al. Global patterns of land-atmosphere fluxes of carbon dioxide, latent heat, and sensible heat derived from eddy covariance, satellite, and meteorological observations. J. Geophys. Res. 116, G00J07 (2011).

    Article  Google Scholar 

  30. Taylor, K. E., Stouffer, R. J. & Meehl, G. A. An overview of CMIP5 and the experiment design. Bull. Amer. Meteorol. Soc. 90, 1467–1485 (2011).

    Google Scholar 

Download references


C.R.S., C.A.W. and K.S. were supported by the US National Science Foundation grant ATM-0910766. C.A.W. was additionally supported through NASA Terrestrial Ecology award NNX10AR68G (2N041). B.E.L. was supported by AmeriFlux (the Office of Science (BER), US Department of Energy (DE-FG02-04ER63917 and DE-FG02-04ER63911)). K.T.P.U. was supported by the US National Science Foundation grant F1137306/MIT subaward 5710003122 to the University of California, Davis. We acknowledge the World Climate Research Programme’s Working Group on Coupled Modelling, which is responsible for CMIP, and we thank the climate modelling groups (Supplementary Table S4) for producing and making available their model output. For CMIP the US Department of Energy’s Program for Climate Model Diagnosis and Intercomparison provided coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. CarbonTracker 2011 results provided by NOAA ESRL, Boulder, Colorado, USA from the website at Jena CO2 inversion results provided courtesy of C. Rödenbeck, Max Planck Institute for Biogeochemistry, Jena, Germany.

Author information

Authors and Affiliations



C.R.S., C.A.W. and K.S. designed the study and are responsible for the integrity of the manuscript; C.R.S. carried out the analysis and all calculations. C.R.S., with C.A.W. and K.S., wrote the manuscript. D.B., T.A.B., A.H.G., B.E.L., W.C.O., K.T.P.U. and R.L.S. contributed FLUXNET data. All authors discussed and commented on the manuscript.

Corresponding author

Correspondence to Christopher R. Schwalm.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 947 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Schwalm, C., Williams, C., Schaefer, K. et al. Reduction in carbon uptake during turn of the century drought in western North America. Nature Geosci 5, 551–556 (2012).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


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