Published by the American Geophysical Union as part of theCoastal and Estuarine Studies, Volume 61.
The effects of increased atmospheric carbon dioxide and relatedclimate change on shallow coral reefs are gaining considerableattention for scientific and economic reasons worldwide. Althoughincreased scientific research has improved our understanding of theresponse of coral reefs to climate change, we still lack keyinformation that can help guide reef management. Research andmonitoring of coral reef ecosystems over the past few decades havedocumented two major threats related to increasing concentrationsof atmospheric CO2: (1) increased sea surface temperatures and (2)increased seawater acidity (lower pH). Higher atmospheric CO2levels have resulted in rising sea surface temperatures and provento be an acute threat to corals and other reef-dwelling organisms.Short periods (days) of elevated sea surface temperatures by aslittle as 1–2°C above the normal maximum temperature hasled to more frequent and more widespread episodes of coralbleaching-the expulsion of symbiotic algae. A more chronicconsequence of increasing atmospheric CO2 is the lowering of pH ofsurface waters, which affects the rate at which corals and otherreef organisms secrete and build their calcium carbonate skeletons.Average pH of the surface ocean has already decreased by anestimated 0.1 unit since preindustrial times, and will continue todecline in concert with rising atmospheric CO2. Theseclimate-related Stressors combined with other direct anthropogenicassaults, such as overfishing and pollution, weaken reef organismsand increase their susceptibility to disease.