Downscaled climate model projections of coral bleaching conditions
(4-km resolution)

For projections of coral bleaching in the original climate model 1° resolution, see here.

Bleaching events are expected to become more frequent and more severe in the decades ahead. This site presents climate model projections of the timing of 2x per decade and 10x per decade (i.e. annual) occurrence of severe bleaching conditions (i.e. thermal stress >8 DHWs). Coral communities will start to change when bleaching becomes more frequent than 2x per decade. Corals susceptible to bleaching will be less common and the structural complexity of many coral reefs will decline. These changes will occur more rapidly if/when bleaching events begin to occur annually. The projections for the two bleaching scenarios have been produced for emissions scenarios RCP8.5 and RCP4.5 (4 projections in total). RCP8.5 is a 'no climate policy' scenario that assumes emissions increase unabated. At time of writing in May of 2016, emissions concentrations were greater than what RCP8.5 projected for 2016. RCP4.5 assumes emissions stabilize just after 2100 due to successful implementation of climate policies that reduce emissions.

These projections are unique in that they have been produced through statistical downscaling so have high-resolution (4-km) relative to raw climate model data (~1x1°); i.e. relative to the projections made available here. The final outputs represent the ensemble average, with 33 climate models (from IPCC CMIP5) used for RCP8.5 and 35 used for RCP4.5. The projections results are available here in the form of Google Earth files, map images, and ArcGIS-compatible spatial data. The projections can also be viewed here on the UNEPLive site under the Coral Reefs theme. The About page on UNEPLive also describes the main findings of this research project and discusses the conservation, management and policy applications of the downscaled projections.

Google Earth Files

Note: We encourage all viewers to read the Contents Descriptions found in each GE file by selecting the 'About this product' page. This page appears at the top of the file directory structure containing the images (see "My Places" in the left-hand side of the Google Earth interface).

RCP4.5_downscaled bleaching projections (kmz file, 13.6MB)
RCP8.5_downscaled bleaching projections (kmz file, 14.1MB)

Problems viewing these files are likely to have one of three causes: 1) you need to clear everything from your 'My Places' folder or need to de-select anything saved there; 2) you need to download the most current version of Google Earth from this link; or 3) the limitations of your PC or graphics card don't allow for the file to be viewed.

Map Images

RCP4.5_2x_per_decade_bleaching_conditions.jpg (7MB)
RCP4.5_annual_severe_bleaching.jpg (7MB)
RCP8.5_2x_per_decade_bleaching_conditions.jpg (7MB)
RCP8.5_annual_severe_bleaching.jpg (7MB)

Spatial Data

You can view and save the spatial data in ArcMap by opening the layer package below. The file will open automatically and show the four projections data layers and the reef locations. Coral reef locations shown here at 4-km resolution combine three published global reef-locations datasets (ReefBase, Millennium Maps, and Reefs at Risk-Revisited). Other known reef locations were added as were any pixels surrounding US-affiliated Pacific Islands with any bottom <30 m deep.

van_Hooidonk_et_al._Downscaled_Bleaching_Projections.lpk (4MB)

The names of models used in the projections can be found here.

The downscaled bleaching projections can also be viewed under the Coral Reef theme within UNEP Live.

Financial and in-kind support for this research was provided by: NOAA Coral Reef Conservation Program, NOAA Atlantic Oceanographic and Meteorological Laboratory, NOAA National Marine Fisheries Service via the PIFSC, World Wildlife Fund, UNEP, USGS via the Pacific Islands Climate Science Center, the Pacific Islands Climate Change Cooperative, RSMAS at the University of Miami and the European Research Council.


Any information used from the downscaled bleaching projections should be cited as 'van Hooidonk et al. (in review)'. Information used from the model-resolution projections for bleaching, acidification and calcification should be cited as 'van Hooidonk et al. (2014)'. Images screen captured from the Google Earth file should always appear with 'adapted from van Hooidonk et al.' if used in presentations or reports.

Please email Ruben van Hooidonk at if you have questions about the projections and methods, or wish to discuss available formats for these data.


van Hooidonk R, Maynard J, Liu Y, Lee SK (2015) Downscaled projections of Caribbean coral bleaching that can inform conservation planning. Global Change Biology, 21(9), 3389-3401

van Hooidonk R, Maynard J, Manzello D, Planes S (2014) Opposite latitudinal gradients in projected ocean acidification and bleaching impacts on coral reefs. Global Change Biology, doi: 10.1111/gcb.12394.

van Hooidonk R, Maynard J, Planes S (2013) Temporary refugia for coral reefs in a warming world. Nature Climate Change, 3, 508-511, doi: 10.1038/nclimate1829.


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