Wednesday, August 29, 2007

Greenhouse gases killing corals

Reference: Study finds Pacific coral reefs dying faster than expected, Bangkok Post, August 28, 2007

The article cites a study to support the thesis that greenhouse gases from fossil fuels are killing off the corals and endangering the ecosystems and economic value of coral reefs. The study in question is actually a survey of surveys. It aggregates data from 6,001 surveys of coral reefs that were made between 1968 and 2004. Each of these surveys provides data for a single reef taken at a single point in time and contains information on the percent of the reef surface that covered by live coral. Only about 10% of the surveys provides data for the same reef later in time and those data are heavily weighted by repeated studies of a handful of reefs. These data do not contain trend information for the Indo-Pacific region as a whole. The reported trend is not credible particularly when one has to pick and choose a time frame in which one can get the desired result. The chosen time frame happens to contain 1998 when El Nino is thought to have caused widespread damage to coral reefs in this region. Yet another limitation of this study is that it only reports a trend and it does not investigate the causes that may be responsible for the trend. This study does not support the article's thesis that greenhouse gases are killing off reef coral.

Cha-am Jamal
August, 2007

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