12th Pacific Science Inter-Congress, 8-12 July 2013
University of the South Pacific, Laucala Bay Campus, Suva, Fiji
Temporary refugia for coral reefs in an
era of climate change and ocean
acidification
Ruben van Hooidonk1 , Jeffrey Maynard2, and Serge Planes2
1
NOAA Atlantic Oceanographic and Meteorological
Laboratory 4301 Rickenbacker Causeway, Miami, FL
33149, USA
USR 3278 CNRS-EPHE, CRIOBE, BP 1013 Papetoai
98729, Moorea - Polynesie Francaise.
2
One of the climate change impacts expected on coral
reefs is an increase in the frequency and severity of
temperature-induced bleaching events. Bleaching causes
mortality when temperature stress persists but future
exposure to bleaching conditions is not expected to be
spatially uniform at the regional or global scale. We
recently produced the first maps of global projections of
bleaching conditions based on ensembles of IPCC AR5
models forced with the new representative concentration
pathway (RCP) experiments (in press at Nature Climate
Change). For the three RCPs with the greatest CO2
emissions (RCP 4.5, 6.0 and 8.5) the onset of annual
bleaching conditions is associated with ~510 ppm CO2
equivalent; the median year of all locations is 2040 for
the fossil-fuel aggressive RCP8.5. Spatial patterns in the
12th Pacific Science Inter-Congress, 8-12 July 2013
University of the South Pacific, Laucala Bay Campus, Suva, Fiji
onset of annual bleaching conditions are similar for each
of the RCP experiments. For RCP8.5, 26% of reef cells
are projected to experience annual bleaching conditions
>5 years later than the median. Some of these very
temporary refugia include the western Indian Ocean,
Thailand, the southern Great Barrier Reef and central
French Polynesia. A reduction in the growth of
greenhouse gas emissions corresponding to the
difference between RCP8.5 and 6.0 delays annual
bleaching in ~23% of reef cells more than two decades,
which might conceivably increase the potential for these
reefs to cope with these changes. We are currently
working to produce projections for ocean acidification
also based on ensembles of IPCC AR5 models. Our
early results suggest acidification will affect higher
latitude reefs earlier potentially negating any benefit to
those reefs of the delayed onset of annual bleaching
conditions. Between now and July our climate model
projections will be collated for coral reef managers in an
interactive Google Earth tool. Our research and the
tool’s development have been made possible by the
Pacific Islands Climate Change Cooperative.
Key Words: coral reefs, climate change, acidification,
management