Combined Biological Sciences Meeting

Centre for Marine Studies
University of Queensland

Coral reefs, climate change and people: Is there any hope for coral reef ecosystems?

Coral reefs are the most biologically diverse ecosystem in the ocean, providing habitat for 1-9 million species and ecological services that are critically important to tropical coastal societies worldwide.  Despite their importance, coral reefs are disappearing at the rate of 1-2% per year (Bruno and Selig 2007) and we may have already lost 40% of these important ecosystems over the past 40 years.   The degradation of coral reefs is being driven by increasing local threats (pollution, overfishing, sedimentation and destructive practices), as well as global climate change (global warming and ocean acidification).  Until recently, global threats were considered to be far-off threat.  Recent evidence suggests that changes are now occurring at rates which dwarf those seen over the past million if not 20 million years.  Most of this evidence suggests that the tropical waters will soon surpass the ocean temperatures (+2^oC) and acidities (CO₃^2- < 200 µmol.kg water^-1) that are able to support carbonate coral reefs, with serious consequences for coral reef ecosystems.  The solutions to this global crisis are twofold. The first is that we must act quickly to deeply cut global CO₂ emissions by more than 90% relative to 1990 levels by 2050.  The second is that we must take decisive action to reduce the impact of local threats to coral reefs. The latter is critically important given the growing evidence that reducing local threats will enable coral reefs greater ecological resilience with which to bounce back from global impacts such as mass coral bleaching.  If we take these two steps over the next decade, there is considerable hope for our precious coral reefs.  If we don't, coral reefs will be a distant memory by the end of this century, with huge consequences for coastal societies worldwide.

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