Read here.
"The first of these studies indicates that "large species of branching Acropora corals dominated shallow reefs in the tropical western Atlantic for at least half a million years until the 1980s, when they declined dramatically." The second study indicates that throughout this long period of time, the earth experienced several glacial/interglacial cycles for which we have good proxy temperature data, and that the four interglacials that preceded the one in which we now live were all warmer than the current one -- and by an average of more than 2°C! Hence, the Acropora corals that have taken such a nosedive in health -- and actual existence -- over the past quarter century are clearly able to tolerate temperatures significantly in excess of those of the present (all else being equal), which current temperatures may also be less than temperatures experienced during the Holocene Climatic Optimum and the Medieval Warm Period of only a few and one thousand years ago, respectively......the study of Gardner et al. (2003a), who assessed the extent of decline in coral cover across the Caribbean via a meta-analysis of data obtained from a total of 263 sites described in 65 scientific studies. This effort revealed, in their words, "a massive region-wide decline of corals across the entire Caribbean basin, with the average hard coral cover on reefs being reduced by 80%, from about 50% to 10% cover, in three decades." However, they also report that "the rate of coral loss has slowed in the past decade compared to the 1980s," and they say "there is no convincing evidence yet that global stressors (e.g. temperature-induced bleaching and reduced rates of carbonation via enhanced levels of atmospheric CO2) are responsible for the overall pattern of these recent coral declines." Instead, they more logically lay the blame at the feet of "local factors originating both naturally (e.g. disease, storms, temperature stress, predation) and anthropogenically (e.g. over-fishing, sedimentation, eutrophication, habitat destruction)," which they say "are occurring at Caribbean-wide scales.""
