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.

Predicted recurrences of mass coral mortality in the Indian Ocean


In 1998, more than 90% of shallow corals were killed on most Indian Ocean reefs1. High sea surface temperature (SST) was a primary cause2,3, acting directly or by interacting with other factors3,4,5,6,7. Mean SSTs have been forecast to rise above the 1998 values in a few decades2,3; however, forecast SSTs rarely flow seamlessly from historical data, or may show erroneous seasonal oscillations, precluding an accurate prediction of when lethal SSTs will recur. Differential acclimation by corals in different places complicates this further3,7,8. Here I scale forecast SSTs at 33 Indian Ocean sites where most shallow corals died in 1998 (ref. 1) to identify geographical patterns in the timing of probable repeat occurrences. Reefs located 10–15° south will be affected every 5 years by 2010–2025. North and south from this, dates recede in a pattern not directly related to present SSTs; paradoxically, some of the warmest sites may be affected last. Temperatures lethal to corals vary in this region by 6 °C, and acclimation of a modest 2 °C by corals could prolong their survival by nearly 100 years.

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: Coral reef sites in the western Indian Ocean where 1998 SSTs caused mass coral mortality.
Figure 2: Historical and forecast SST data from two sites before and after the transformations.
Figure 3: Probabilities of the warmest months of four sites reaching the lethal 1998 temperatures over time.
Figure 4: ‘Extinction dates’ plotted for coral reef sites on the three transects, showing the date when a probability of 0.2 is reached.
Figure 5: Recession of time to extinction date with imagined acclimation of corals by up to 2 °C with Kenya as the example.


  1. Wilkinson, C. R. in Seas at the Millennium, an Environmental Evaluation vol. 3 (ed. Sheppard, C.) 43–57 (Elsevier, Amsterdam, 2000)

    Google Scholar 

  2. Hoegh-Guldberg, O. Climate change, coral bleaching and the future of the world's coral reefs. Mar. Freshwater Res. 50, 839–866 (1999)

    Article  Google Scholar 

  3. Pittock, A. B. Coral reefs and environmental change: Adaptation to what? Am. Zool. 39, 10–29 (1999)

    Article  Google Scholar 

  4. Turner, J., et al. in Coral Reef Degradation in the Indian Ocean, Status Report 2000 (eds Souter, D., Obura, D. & Linden, O.) 94–107 (CORDIO, Stockholm, 2000)

    Google Scholar 

  5. Nakamura, T. & Woesik, R. Water-flow rates and passive diffusion partially explain differential survival during the 1998 bleaching event. Mar. Ecol. Prog. Ser. 212, 301–304 (2001)

    Article  ADS  Google Scholar 

  6. Sheppard, C. R. C. The main issues affecting coasts of the Indian and western Pacific Oceans: a meta-analysis from seas at the millennium. Mar. Pollut. Bull. 42, 1199–1207 (2001)

    Article  CAS  Google Scholar 

  7. Douglas, A. W. Coral bleaching—how and why? Mar. Pollut. Bull. 46, 385–392 (2003)

    Article  CAS  Google Scholar 

  8. Gates, R. D. & Edmunds, P. J. The physiological mechanisms of acclimatisation in tropical reef corals. Am. Zool. 39, 30–43 (1999)

    Article  Google Scholar 

  9. Wilkinson, C. R. et al. Ecological and socio-economic impacts of 1998 coral mortality in the Indian Ocean: an ENSO (El Niño-Southern Oscillation) impact and a warning of future change? Ambio 28, 188–196 (1999)

    Google Scholar 

  10. Cesar, H. S. J. (ed.) Economics of Coral Reefs 244 (CORDIO, Kalmar, Sweden, 2000)

  11. Rayner, N. A. et al. Global analyses of SST, sea ice and night marine air temperature since the late nineteenth century. J. Geophys. Res. Atmos. (in the press)

  12. Sheppard, C. R. C. & Rayner, N. Utility of the Hadley Centre sea ice and surface temperature data set (HadISST1) in two widely contrasting coral reef areas. Mar. Pollut. Bull. 44, 303–308 (2002)

    Article  CAS  Google Scholar 

  13. McAvaney, B. J. et al. Climate Change 2001: The Scientific Basis. Intergovernmental Panel on Climate Change (ed. Houghton, J. T. et al.) 471–523 (Cambridge Univ. Press, Cambridge, UK, 2001)

    Google Scholar 

  14. Cubasch, U. et al. Climate Change 2001: The Scientific Basis. Intergovernmental Panel on Climate Change (ed. Houghton, J. T. et al.) 525–582 (Cambridge University Press, Cambridge, UK, 2001)

    Google Scholar 

  15. Sheppard, C. R. C. & Loughland, R. Coral mortality and recovery in response to increasing temperature in the southern Arabian Gulf. Aquat. Ecosyst. Health Mgmt 5, 395–402 (2002)

    Article  Google Scholar 

  16. Veron, J. E. N. Corals of the World vols 1–3 (Australian Institute of Marine Science, Townsville, Australia, 2000)

    Google Scholar 

  17. Sheppard, C. R. C. & Sheppard, A. L. S. Corals and coral communities of Arabia. Fauna Saudi Arabia 12, 7–192 (1991)

    Google Scholar 

  18. Sheppard, C. R. C., Spalding, M., Bradshaw, C. & Wilson, S. Erosion vs. recovery of coral reefs after 1998 El Niño: Chagos reefs, Indian Ocean. Ambio 31, 40–48 (2002)

    Article  Google Scholar 

  19. Linden, O., Souter, D., Wilhemsson, D. & Obura, D. Coral Reef Degradation in the Indian Ocean, Status Report 2002 284 (CORDIO, Kalmar, Sweden, 2002)

    Google Scholar 

  20. Riegl, B. Effects of the 1996 and 1998 positive sea-surface temperature anomalies on corals, coral diseases and fish in the Arabian Gulf (Dubai, UAE). Mar. Biol. 140, 29–40 (2002)

    Article  Google Scholar 

  21. McClanahan, T. R. Bleaching damage and recovery potential of Maldivian coral reefs. Mar. Pollut. Bull. 40, 587–597 (2000)

    Article  CAS  Google Scholar 

  22. Spencer, T., Teleki, K. A., Bradshaw, C. & Spalding, M. D. Coral bleaching in the southern Seychelles during the 1997–1998 Indian Ocean warm event. Mar. Pollut. Bull. 40, 569–586 (2000)

    Article  CAS  Google Scholar 

  23. Harrison, P. L. & Wallace, C. C. in Coral Reefs (ed. Dubinsky, Z.) 133–206 (Elsevier, Amsterdam, 1990)

    Google Scholar 

  24. Sheppard, C. R. C. & Salm, R. V. Reefs and corals of Oman, with a description of a new species of coral (Scleractinia, Acanthastrea). J. Nat. Hist. 22, 263–279 (1988)

    Article  Google Scholar 

Download references


The HadCM3 data were provided by the Hadley Centre for Climate Research through D. Viner, who also provided information on the data's characteristics. I thank M. Keeling and G. Medley for advice on analyses; N. Rayner of the Hadley Centre for information on the HadISST1 data and for communicating results before publication; and O. Langmead and A. Edwards for assistance with data extraction.

Author information

Authors and Affiliations


Ethics declarations

Competing interests

The author declares that he has no competing financial interests.

Supplementary information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Sheppard, C. Predicted recurrences of mass coral mortality in the Indian Ocean. Nature 425, 294–297 (2003).

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