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.

  • Letter
  • Published:

Civil conflicts are associated with the global climate

Abstract

It has been proposed that changes in global climate have been responsible for episodes of widespread violence and even the collapse of civilizations1,2. Yet previous studies have not shown that violence can be attributed to the global climate, only that random weather events might be correlated with conflict in some cases3,4,5,6,7. Here we directly associate planetary-scale climate changes with global patterns of civil conflict by examining the dominant interannual mode of the modern climate8,9,10, the El Niño/Southern Oscillation (ENSO). Historians have argued that ENSO may have driven global patterns of civil conflict in the distant past11,12,13, a hypothesis that we extend to the modern era and test quantitatively. Using data from 1950 to 2004, we show that the probability of new civil conflicts arising throughout the tropics doubles during El Niño years relative to La Niña years. This result, which indicates that ENSO may have had a role in 21% of all civil conflicts since 1950, is the first demonstration that the stability of modern societies relates strongly to the global climate.

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

Access options

Buy this article

Purchase on Springer Link

Instant access to full article PDF

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

Figure 1: ENSO exposure over space and time.
Figure 2: Conflict risk associated with ENSO.
Figure 3: ENSO, ACR and income.

Similar content being viewed by others

References

  1. Homer-Dixon, T. F. On the threshold: environmental changes as causes of acute conflict. Int. Secur. 16, 76–116 (1991)

    Article  Google Scholar 

  2. Diamond, J. Collapse: How Societies Choose to Fail or Succeed (Viking, 2005)

    Google Scholar 

  3. Miguel, E., Satyanath, S. & Sergenti, E. Economic shocks and civil conflict: an instrumental variables approach. J. Polit. Econ. 112, 725–753 (2004)

    Article  Google Scholar 

  4. Levy, M. A., Thorkelson, C., Vorosmarty, C., Douglas, E. & Humphreys, M. Paper presented at the International Workshop for Human Security and Climate Change, Oslo, Norway, 21–23 June 2005.

    Google Scholar 

  5. Burke, M., Miguel, E., Satyanath, S., Dykema, J. & Lobell, D. Warming increases risk of civil war in Africa. Proc. Natl Acad. Sci. USA 106, 20670–20674 (2009)

    Article  ADS  CAS  Google Scholar 

  6. Sandholt, J. P. & Gleditsch, K. S. Rain, growth, and civil war: the importance of location. Defence Peace Econ. 20, 359–372 (2009)

    Article  Google Scholar 

  7. Buhaug, H. Climate not to blame for African civil wars. Proc. Natl Acad. Sci. USA 107, 16477–16482 (2010)

    Article  ADS  CAS  Google Scholar 

  8. Ropelewski, C. F. & Halpert, M. S. Global and regional precipitation patterns associated with the El Niño/Southern Oscillation. Mon. Weath. Rev. 115, 1606–1626 (1987)

    Article  ADS  Google Scholar 

  9. Chiang, J. C. H. & Sobel, A. H. Tropical tropospheric temperature variations caused by ENSO and their influence on the remote tropical climate. J. Clim. 15, 2616–2631 (2002)

    Article  ADS  Google Scholar 

  10. Sarachik, E. S. & Cane, M. A. The El Niño-Southern Oscillation Phenomenon (Cambridge Univ. Press, 2010)

    Book  Google Scholar 

  11. Grove, R. H. The great El Niño of 1789–93 and its global consequences: Reconstructing an extreme climate event in world environmental history. Mediev. Hist. J. 10, 75–98 (2007)

    Article  Google Scholar 

  12. Davis, M. Late Victorian Holocausts: El Niño Famines and the Making of the Third World (Verso, 2002)

    Google Scholar 

  13. Fagan, B. Floods, Famines and Emperors: El Niño and the Fate of Civilizations (Basic Books, 2009)

    Google Scholar 

  14. Salehyan, I. From climate change to conflict? No consensus yet. J. Peace Res. 45, 315–326 (2008)

    Article  Google Scholar 

  15. Zhang, D. D. et al. Global climate change, war and population decline in recent human history. Proc. Natl Acad. Sci. USA 104, 19214–19219 (2007)

    Article  ADS  CAS  Google Scholar 

  16. Tol, R. S. J. & Wagner, S. Climate change and violent conflict in Europe over the last millennium. Clim. Change 99, 65–79 (2009)

    Article  ADS  Google Scholar 

  17. Strand, H. Onset of Armed Conflict: A New List for the Period 1946–2004, with Applications. Technical report 〈http://www.prio.no/CSCW/Datasets/Armed-Conflict〉 (Center for the Study of Civil War, 2006)

    Google Scholar 

  18. Blattman, C. & Miguel, E. Civil war. J. Econ. Lit. 48, 3–57 (2010)

    Article  Google Scholar 

  19. Holland, P. W. Statistics and causal inference. J. Am. Stat. Assoc. 81, 945–960 (1986)

    Article  MathSciNet  Google Scholar 

  20. Rosenzweig, C. & Hillel, D. Climate Variability and the Global Harvest: Impacts of El Niño and Other Oscillations on Agro-ecosystems (Oxford Univ. Press, 2008)

    Google Scholar 

  21. Hsiang, S. M. Temperatures and cyclones strongly associated with economic production in the Caribbean and Central America. Proc. Natl Acad. Sci. USA 107, 15367–15372 (2010)

    Article  ADS  CAS  Google Scholar 

  22. Jones, B. & Olken, B. Climate shocks and exports. Am. Econ. Rev. 100, 454–459 (2010)

    Article  Google Scholar 

  23. Chen, D., Cane, M., Kaplan, A., Zebiak, S. & Huang, D. Predictability of El Niño over the past 148 years. Nature 428, 733–736 (2004)

    Article  ADS  CAS  Google Scholar 

  24. Schlenker, W. & Roberts, M. Nonlinear temperature effects indicate severe damages to U.S. crop yields under climate change. Proc. Natl Acad. Sci. USA 106, 15594–15598 (2009)

    Article  ADS  CAS  Google Scholar 

  25. Carmargo, S. J. & Sobel, A. H. Western North Pacific tropical cyclone intensity and ENSO. J. Climate 18, 2996–3006 (2005)

    Article  ADS  Google Scholar 

  26. Kovats, R. S., Bouma, M. J., Hajat, S., Worrall, E. & Haines, A. El Niño and health. Lancet 12, 917–932 (2003)

    Google Scholar 

  27. Larrick, R. P., Timmerman, T. A., Carton, A. M. & Abrevaya, J. Temper, temperature, and temptation: heat-related retaliation in baseball. Psychol. Sci. 22, 423–428 (2011)

    Article  Google Scholar 

  28. Brunner, A. D. El Niño and world primary commodity prices: warm water or hot air? Rev. Econ. Stat. 84, 176–183 (2002)

    Article  Google Scholar 

Download references

Acknowledgements

S.M.H. was supported by Environmental Protection Agency Science to Achieve Results grant FP-916932 and a postdoctoral fellowship in Applied Econometrics at the National Bureau of Economic Research; K.C.M. was supported by the Paul and Daisy Soros Fellowship for New Americans. We thank W. B. MacLeod, B. Salanié, A. Sobel, J. Sachs, W. Schlenker, E. Miguel, D. Almond, S. Barrett, G. Heal, M. Neidell, J. Mutter, N. Keohane, A. Cassella, J. Currie, W. Kopczuk, C. Pop-Eleches, R. Fisman, S. Naidu, M. Humphreys, D. Lobell, M. Roberts, M. Greenstone, M. Biasutti, G. Wagner, G. McCord, J. Anttila-Hughes, R. Fishman, A. Tompsett, A. Neal, B. R. Chen and seminar participants at Columbia, Massachusetts Institute of Technology, Stanford, University of California Santa Barbara, Environmental Defense Fund, the National Bureau of Economic Research Summer Institute and the American Geophysical Union Fall Meeting for suggestions. We also thank H. Buhaug and M. Burke for sharing replication materials.

Author information

Authors and Affiliations

Authors

Contributions

S.M.H. conceived and designed the study. S.M.H. and K.C.M. conducted the analysis. S.M.H., K.C.M. and M.A.C. wrote the paper.

Corresponding author

Correspondence to Solomon M. Hsiang.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Tables 1-14, Supplementary Figures 1-12 with legends, Supplementary Methods and additional references. (PDF 5976 kb)

Supplementary Data

This file contains STATA datasets and STATA code to replicate the results of this study. Results can be automatically replicated using STATA software version 11.1 or later. (ZIP 1748 kb)

PowerPoint slides

Rights and permissions

Reprints and permissions

About this article

Cite this article

Hsiang, S., Meng, K. & Cane, M. Civil conflicts are associated with the global climate. Nature 476, 438–441 (2011). https://doi.org/10.1038/nature10311

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature10311

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