Humans Are Destroying Earth's Coral Reefs
Seiler, T.J., Rasse, D.P., Li, J., Dijkstra, P., Anderson, H.P., Johnson, D.P., Powell, T.L., Hungate, B.A., Hinkle, C.R. and Drake, B.G. 2009. Disturbance, rainfall and contrasting species responses mediated aboveground biomass response to 11 years of CO2 enrichment in a Florida scrub-oak ecosystem. Global Change Biology 15: 356-367.
The five U.S. researchers begin their analysis of the subject by noting that "coral reefs, similar to those we know today, have existed for approximately 215 million years (and, in another taxonomic guise, for about 500 million years)," even surviving the turmoil that brought about "the extinction of the dinosaurs and the climate changes of the ice ages," which known facts would seem to suggest, in their words, that earth's corals possess a "remarkable evolutionary resilience," which "would certainly suggest," as they describe it, that "there is scope for ecological resilience as well." So why are earth's coral reefs in so much trouble today?
Clearly, all forms of life on earth are subject to various environmental challenges that periodically threaten their existence on a large spatial scale; and corals are no exception. Tectonic upheavals, asteroid impacts, natural climate changes, disease pandemics and predator outbreaks: all of these challenges and many others confront earth's biosphere on a variety of different time scales and to a greater or lesser degree. So what is the cause of the current coral crisis?
The problem, as we and many others see it, is a whole set of what Riegl et al. describe as "smaller-scale, localized, and entirely man-made threats," among which they list "runoff, sedimentation, and nutrient enrichment; coastal construction leading to smothering of habitat and creation of high turbidity around coasts; overfishing and destructive fishing." In a study designed to reconstruct multi-century histories of fourteen coral reefs from various places around the world, for example, Pandolfi et al. (2003) found that "all reefs were substantially degraded long before outbreaks of coral disease and bleaching." In fact, they determined that the "degradation of coral reef ecosystems began centuries ago," when the world was in the midst of the Little Ice Age and the air's CO2 concentration was a hundred parts per million less than it is today. It is our belief, therefore, that this long-term degradation has severely weakened the ability of many of earth's corals to adequately cope with the challenges of temperature-induced bleaching and potential ocean acidification.
So how far down the slippery slope that leads to extinction were the world's coral reefs at the start of the current century? Pandolfi et al.'s analysis revealed that the 14 reefs they studied were fairly evenly distributed between just under 30% to just under 80% of the way from what they call "pristine" to "ecologically extinct," and that "recent widespread and catastrophic episodes of coral bleaching and disease have distracted attention from the chronic and severe historical decline of reef ecosystems."
In describing the practical implications of their findings, Pandolfi et al. concluded that "coral reef ecosystems will not survive for more than a few decades unless they are promptly and massively protected from human exploitation." To claim that we must drastically reduce anthropogenic CO2 emissions to save earth's corals from extinction, as most climate alarmists contend we must do, is to look beyond the mark, and to therefore likely fail to implement the more mundane (but absolutely necessary) local protective measures that must be put in place now.
Pandolfi, J.M., Bradbury, R.H., Sala, E., Hughes, T.P., Bjorndal, K.A., Cooke, R.G., McArdle, D., McClenachan, L., Newman, M.J.H., Paredes, G., Warner, R.R. and Jackson, J.B.C. 2003. Global trajectories of the long-term decline of coral reef ecosystems. Science 301: 955-958.
Riegl, B., Bruckner, A., Coles, S.L., Renaud, P. and Dodge, R.E. 2009. Coral Reefs: Threats and conservation in an era of global change. Annals of the New York Academy of Sciences 1162: 136-186.
Wilkinson, C. 2006. Status of coral reefs of the world: Summary of threats and remedial action. In: Cote, I.M. and Reynolds, J.D. (Eds.), Coral Reef Conservation, Zoological Society of London, Cambridge University Press, Cambridge, UK, p. 4-39.