Letter | Published:

Civil conflicts are associated with the global climate

Nature volume 476, pages 438441 (25 August 2011) | Download Citation


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.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1.

    On the threshold: environmental changes as causes of acute conflict. Int. Secur. 16, 76–116 (1991)

  2. 2.

    Collapse: How Societies Choose to Fail or Succeed (Viking, 2005)

  3. 3.

    , & Economic shocks and civil conflict: an instrumental variables approach. J. Polit. Econ. 112, 725–753 (2004)

  4. 4.

    , , , & Paper presented at the International Workshop for Human Security and Climate Change, Oslo, Norway, 21–23 June 2005.

  5. 5.

    , , , & Warming increases risk of civil war in Africa. Proc. Natl Acad. Sci. USA 106, 20670–20674 (2009)

  6. 6.

    & Rain, growth, and civil war: the importance of location. Defence Peace Econ. 20, 359–372 (2009)

  7. 7.

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

  8. 8.

    & Global and regional precipitation patterns associated with the El Niño/Southern Oscillation. Mon. Weath. Rev. 115, 1606–1626 (1987)

  9. 9.

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

  10. 10.

    & The El Niño-Southern Oscillation Phenomenon (Cambridge Univ. Press, 2010)

  11. 11.

    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)

  12. 12.

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

  13. 13.

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

  14. 14.

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

  15. 15.

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

  16. 16.

    & Climate change and violent conflict in Europe over the last millennium. Clim. Change 99, 65–79 (2009)

  17. 17.

    Onset of Armed Conflict: A New List for the Period 1946–2004, with Applications. Technical report 〈〉 (Center for the Study of Civil War, 2006)

  18. 18.

    & Civil war. J. Econ. Lit. 48, 3–57 (2010)

  19. 19.

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

  20. 20.

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

  21. 21.

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

  22. 22.

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

  23. 23.

    , , , & Predictability of El Niño over the past 148 years. Nature 428, 733–736 (2004)

  24. 24.

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

  25. 25.

    & Western North Pacific tropical cyclone intensity and ENSO. J. Climate 18, 2996–3006 (2005)

  26. 26.

    , , , & El Niño and health. Lancet 12, 917–932 (2003)

  27. 27.

    , , & Temper, temperature, and temptation: heat-related retaliation in baseball. Psychol. Sci. 22, 423–428 (2011)

  28. 28.

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

Download references


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

Author notes

    • Solomon M. Hsiang

    Present address: Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, New Jersey 08544, USA.


  1. School of International and Public Affairs, Columbia University, New York, New York 10027, USA

    • Solomon M. Hsiang
    •  & Kyle C. Meng
  2. Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964, USA

    • Mark A. Cane


  1. Search for Solomon M. Hsiang in:

  2. Search for Kyle C. Meng in:

  3. Search for Mark A. Cane in:


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.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Solomon M. Hsiang.

Supplementary information

PDF files

  1. 1.

    Supplementary Information

    This file contains Supplementary Tables 1-14, Supplementary Figures 1-12 with legends, Supplementary Methods and additional references.

Zip files

  1. 1.

    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.

About this article

Publication history






Further reading


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.