A comparison of the 1998 and 2002 coral bleaching events on the Great Barrier Reef: spatial correlation, patterns, and predictions


Detailed mapping of coral bleaching events provides an opportunity to examine spatial patterns in bleaching over scales of 10 s to 1,000 s of km and the spatial correlation between sea surface temperature (SST) and bleaching. We present data for two large-scale (2,000 km) bleaching events on the Great Barrier Reef (GBR): one from 1998 and another from 2002, both mapped by aerial survey methods. We examined a wide range of satellite-derived SST variables to determine which one best correlated with the observed bleaching patterns. We found that the maximum SST occurring over any 3-day period (max3d) during the bleaching season predicted bleaching better than anomaly-based SST variables and that short averaging periods (3–6 days) predicted bleaching better than longer averaging periods. Short periods of high temperature are therefore highly stressful to corals and result in highly predictable bleaching patterns. Max3d SST predicted the presence/absence of bleaching with an accuracy of 73.2%. Large-scale (GBR-wide) spatial patterns of bleaching were similar between 1998 and 2002 with more inshore reefs bleached compared to offshore reefs. Spatial change in patterns of bleaching occurred at scales of ~10 s km, indicating that reefs bleach (or not) in spatial clusters, possibly due to local weather patterns, oceanographic conditions, or both. Approximately 42% of reefs bleached to some extent in 1998 with ~18% strongly bleached, while in 2002, ~54% of reefs bleached to some extent with ~18% strongly bleached. These statistics and the fact that nearly twice as many offshore reefs bleached in 2002 compared to 1998 (41 vs. 21%, respectively) makes the 2002 event the worst bleaching event on record for the GBR. Modeling of the relationship between bleaching and max3d SST indicates that a 1 °C increase would increase the bleaching occurrence of reefs from 50% (approximate occurrence in 1998 and 2002) to 82%, while a 2 °C increase would increase the occurrence to 97% and a 3 °C increase to 100%. These results suggest that coral reefs are profoundly sensitive to even modest increases in temperature and, in the absence of acclimatization/adaptation, are likely to suffer large declines under mid-range International Panel for Climate Change predictions by 2050.

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

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6


  1. 1.

    In situ temperature data were collected using high-precision (0.02 °C) data loggers (Dataflow Systems) at 1- and 6-m depths at Magnetic Island and an automatic weather station at Davies Reef at 2-m depth. Logger and weather station sensors were calibrated/corrected to an accuracy of ±0.1 °C.


  1. Andréfouët S, Berkelmans R, Odriozola L, Done TJ, Oliver JK, Muller-Krager, FE (2002) Choosing the appropriate spatial resolution for monitoring coral bleaching events using remote sensing. Coral Reefs 21:147–154

    Google Scholar 

  2. Barton IJ (1995) Satellite-derived sea surface temperatures: Current status. J Geophys Res 100:8777–8790

    Google Scholar 

  3. Berkelmans R (2001) Bleaching, upper thermal limits and temperature adaptation in reef corals. PhD Thesis, James Cook University, Townsville

  4. Berkelmans R (2002) Time-integrated thermal bleaching thresholds of reefs and their variation on the Great Barrier Reef. Mar Ecol Prog Ser 229:73–82

    Google Scholar 

  5. Berkelmans R, Oliver JK (1999) Large scale bleaching of corals on the Great Barrier Reef. Coral Reefs 18:55–60

    Article  Google Scholar 

  6. Berkelmans R, Willis BL (1999) Seasonal and local spatial patterns in the upper thermal limits of corals on the inshore central Great Barrier Reef. Coral Reefs 18:219–228

    Google Scholar 

  7. Berkelmans R, Hendee JC, Marshall PA, Ridd PV, Orpin AR, Irvine D (2002) Automatic weather stations: tools for managing and monitoring potential impacts to coral reefs. Mar Technol Soc J 36:29–38

    Google Scholar 

  8. Dennis GD, Wicklund RI (1993) The relationship between environmental factors and coral bleaching at Lee stocking Island, Bahamas in 1990. In: Case histories for the colloquium and forum on global aspects of coral reefs: health, hazards and history, 1993, F15-F21

  9. Done T, Whetton P, Jones R, Berkelmans R, Lough J, Skirving W, Wooldridge S (2003) Global climate and coral bleaching on the Great Barrier Reef. Final report to the State of Queensland Greenhouse Task Force, Department of Natural Resources and Mining, 33 pp, www.nrm.qld.gov.au/science/climate.html

  10. Drollet JH, Faucon M, Maritorena S, Martin PMV (1994) A survey of environmental physico-chemical parameters during a minor coral mass bleaching event in Tahiti in 1993. Aust J Mar Freshwater Res 45:1149–1156

    CAS  Google Scholar 

  11. Fabricius KE, De’ath G (2001) Biodiversity on the Great Barrier Reef: large-scale patterns and turbidity-related loss of taxa. In: Wolanski E (ed) Biological–physical links: oceanographic processes on the Great Barrier Reef. CRC Press, Boca Raton

  12. Fitt WK, McFarlane FK, Warner ME, Chilcoat GC (2000) Seasonal patterns of tissue biomass and densities of symbiotic dinoflagellates in reef corals and relation to coral bleaching. Limnol Oceanogr 45:677–685

    CAS  Google Scholar 

  13. Gleeson MW, Strong AE (1995) Applying MCSST to coral reef bleaching. Advance Space Res 16:151–154

    Article  Google Scholar 

  14. Glynn PW (1993) Coral reef bleaching: ecological perspectives. Coral Reefs 12:1–17

    Google Scholar 

  15. Goreau TJ, Hayes RL (1994) Coral bleaching and ocean ‘Hot Spots’. Ambio 3:176–180

    Google Scholar 

  16. Hastie TJ, Tibshirani RJ (1990) Generalized additive models. Chapman and Hall, London

  17. Hendee JC, Berkelmans R (2002) Expert System generated coral bleaching alerts for Myrmidon and Agincourt Reefs, Great Barrier Reef, Australia. Proc 9th Int Coral Reef Symp, Bali, 2000, vol 2, pp 1099–1104

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

    Google Scholar 

  19. Hopley D (1982) The geomorphology of the Great Barrier Reef : Quaternary development of coral reefs. Wiley-Interscience, New York

    Google Scholar 

  20. Lewis A (2001) Great Barrier Reef Depth and Elevation Model: GBRDEM, CRC-Reef technical report #33, CRC Reef Research Centre, Townsville

    Google Scholar 

  21. Mayer AG (1914) The effects of temperature upon marine animals. Carn Inst Washington Pub Papers Mar Lab Tortugas, vol 6, pp 3–24

  22. McField MD (1999) Coral response during and after mass bleaching in Belize. Bull Mar Sci 64:155–172

    Google Scholar 

  23. Shinn EA (1966) Coral growth-rate, an environmental indicator. J Paleontol 40:233–241

    Google Scholar 

  24. Skirving WJ, Guinotte J (2001) The sea surface temperature story on the Great Barrier Reef during the coral bleaching event of 1998. In: Wolanski E(ed) Oceanographic process of coral reefs: physical and biological links in the Great Barrier Reef. CRC Press, Boca Raton

  25. Skirving WJ, Mahoney M, Steinberg CR (2002) Sea surface atlas of the Great Barrier Reef, 1990–2000. CD Rom, Australian Institute of Marine Science and the CRC Reef Research Center, Townsville

  26. Statistical Sciences (1999) S-PLUS, Version 2000 for Windows, Seattle, a division of Mathsoft Inc., vols 1–4

  27. Strong AE, Barrientos CS, Duda C, Sapper J (1997) Improved satellite techniques for monitoring coral reef bleaching. Proc 8th Int Coral Reef Symp, vol 2, pp 1495–1498

  28. Winter A, Appeldoorn RS, Bruckner A, Williams EH, Goenaga C (1998) Sea surface temperatures and coral reef bleaching off La Parguera, Puerto Rico (northeastern Caribbean Sea). Coral Reefs 17:377–382

    Google Scholar 

  29. Wooldridge S, Done TJ (2003) Learning to predict large-scale coral bleaching from past events: a Bayesian approach using remotely sensed data, in-situ data, and environmental proxies. (in preparation)

  30. Yonge CM, Nicholls AG (1931) Studies on the physiology of corals. IV. The structure, distribution and physiology of the zooxanthellae. Sci Rep Gt Barrier Reef Exped 1928–1929 1:135–176

Download references


We gratefully acknowledge David Wachenfeld, Paul Marshall, and Jessica Hoey for their role in documenting, synthesizing, and communicating the results of the 2002 bleaching event. We also thank Tim Phillips, the crew of the RV Lady Basten, and Queensland Parks and Wildlife Service for their assistance during field surveys. We are also grateful to Coastwatch (Australian Customs Service), their flight crews (Surveillance Australia P/L), and Day-to-Day Management (Queensland Parks and Wildlife Service and the Great Barrier Reef Marine Park Authority) for their cooperation in allowing the principal author to survey many reefs during their routine aerial patrols. The Great Barrier Reef Marine Park Authority funded the balance of the aerial surveys. We are also indebted to Mike Mahoney who shouldered the burden of processing the satellite SST images.

Author information



Corresponding author

Correspondence to Ray Berkelmans.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Berkelmans, R., De’ath, G., Kininmonth, S. et al. A comparison of the 1998 and 2002 coral bleaching events on the Great Barrier Reef: spatial correlation, patterns, and predictions. Coral Reefs 23, 74–83 (2004). https://doi.org/10.1007/s00338-003-0353-y

Download citation


  • Climate change
  • Coral bleaching
  • Great Barrier Reef
  • Sea-surface temperature
  • Spatial correlation