Frequency of Future Coral Reef Bleaching Events

Frequency of projected coral reef bleaching events in the 2030s and 2050s

  • Source: WRI
The Frequency of Future Coral Reef Bleaching Events in the 2030s and 2050s data set was produced by World Resources Institute. It depicts the frequency of future bleaching events in the 2030s and 2050s, as represented by the percentage of years in each decade when a NOAA Bleaching Alert Level 2 (i.e., severe thermal stress) is predicted to occur. These coral bleaching predictions are based on ocean temperature projections under an IPCC A1B (business-as-usual) emissions scenario and adjusted to account for historical temperature variability, but not adjusted by any other resistance or resilience factors. The thermal stress on corals is estimated using the accumulation of “degree heating months” (DHMs) over a 4-month rolling window at 50 km resolution. One DHM (in °C-month) is equal to 1 month of sea surface temperature that is 1°C greater than the maximum in the monthly climatology, known as the maximum monthly mean. The data used to produce this map were adapted from Donner, S.D. 2009 “Coping with Commitment: Projected Thermal Stress on Coral Reefs under Different Future Scenarios.” Resource Watch sh...

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Formal name

Frequency of Future Coral Reef Bleaching Events in the 2030s and 2050s


The data do not account for resistance or resilience factors apart from the historical temperature variability and shows projections for only 1 emissions scenario.

Suggested citation

[1] WRI. 2011. "Frequency of Future Coral Bleaching Effects in the 2030s and 2050s." World Resources Institute. Accessed through Resource Watch, [date]. [2] Donner, S.D. 2009. “Coping with Commitment: Projected thermal stress on coral reefs under different future scenarios.” PLoS ONE 4(6): e5712.Accessed through Resource Watch, [date].


World Resources Institute (WRI)

Geographic coverage


Spatial resolution

50 km

Date of content

2030s, 2050s


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