Coral reef ecosystems are seriously threatened by changing conditions in the ocean. Although many factors are implicated, climate change has emerged as a dominant and rapidly growing threat. Developing a long-term strategic plan for the conservation of coral reefs is urgently needed yet is complicated by significant uncertainty associated with climate change impacts on coral reef ecosystems. In this paper, Hawthorne Beyer and myself applied global datasets on climate change, cyclones and warming to map vulnerability of all coral reefs, then used Modern Portfolio Theory to identify coral reef locations globally that, in the absence of other impacts, are likely to have a heightened chance of surviving projected climate changes relative to other reefs. Long-term planning that is robust to uncertainty in future conditions provides an objective and transparent framework for guiding conservation action and strategic investment. These locations constitute important opportunities for novel conservation investments to secure less vulnerable yet well-connected coral reefs that may, in turn, help to repopulate degraded areas in the event that the climate has stabilized.
Map showing locations of the final 50 reefs identified by the project
Our analysis provides a robust approach to identify portfolios of coral reef conservation options under climate impacts that explicitly reduces risk arising from uncertainties in future conditions. Of particular interest are places where there is currently little conservation attention, but where climate impacts may be relatively low–‐such as northern Sumatra and the southern Red Sea. In reality, some of these areas may already be highly degraded, but could still represent important conservation opportunities, due to their projected long‐term prospects of more suitable environmental conditions. Reefs in BCUs that are degraded due to tractable local threats (e.g. solving water quality problems or managing exploitation) may also represent key opportunities for effective conservation intervention, as the transition from a degraded to a “healthy” and biodiverse reef can restore many now‐absent ecological, economic, and social benefits.
Figure from the paper shows some of the 50 reef solutions, identified using Modern Portfolio Theory. Solutions to the 50 reef problem vary based on the amount of risk investors are willing to take, with maximum return (purple and orange in middle panel) and balanced solutions (purple and green in middle panel) shown here. The balanced scenario represents the optimal portfolio presented in this paper. (Colors of BCUs in the other panels have no significance and serve only to distinguish individual BCUs).
Beyer HL, Kennedy EV, Beger M, Chen CA, Cinner JE, Darling ES, Eakin CM, Gates RD, Heron SF, Knowlton N, Obura DO, Palumbi SR, Possingham HP, Puotinen M, Runting RK, Skirving WJ, Spalding M, Wilson KA, Wood S, Veron JE, Hoegh‐Guldberg, O. 2018. Risk‐sensitive planning for conserving coral reefs under rapid climate change. Conservation Letters. 2018;e12587.