More than half of the world's coral reefs may be lost by the end of this century, according to a new scientific report.

And, although Bermuda has not yet been affected as badly as in the Caribbean, global warming may speed up the death of coral reefs surrounding the Island as well.

Global warming, which raises the temperature of the world's oceans, is killing off corals by causing them to eject algae which is essential to their overall health and gives them their bright colours. The resulting “bleached” corals are more susceptible to diseases, grow slowly and fail to reproduce.

Bleaching events in Bermuda have been less frequent than those in the Caribbean, where coral cover in some areas has declined by up to 80 percent over the last three decades, said Bermuda Biological Station for Research (BBSR) postdoctoral scientist Dr. Samantha de Putron.

However, global warming may cause increased incidents to occur here also, she warned.

A statement said BBSR's Benthic Ecology Research Programme, which undertakes long-term monitoring of Bermuda's coral reefs, last summer observed record high levels of bleaching on Bermuda's offshore reefs, which resulted in the mortality of some corals.

A report, “Coral Reefs and Global Climate Change”, issued last month by the Pew Centre on Global Climate Change, said coral coral reef degradation is mainly caused by human activities, including coastal development, over-fishing and pollution. According to the report, climate change was also labelled responsible for coral reef loss.

“A clear message from the report is that climate change is yet another detriment to coral reefs that are already severely impacted by many stress factors, ranging from over-harvesting to nutrient and sediment loading,” said Dr. de Putron, who has been studying coral health at BBSR since 1998.

The Pew report also indicates that changes in ocean chemistry, caused by increased atmospheric concentrations of carbon dioxide, may impact coral health. BBSR scientists are investigating the effect of elevated concentrations of carbon dioxide on coral. Preliminary research indicates the future health of this ecosystem may be at risk as carbon dioxide hampers the ability of coral to produce their hard skeletons of calcium carbonate.

BBSR also maintains several long-term monitoring sites to measure the impacts of direct human activity on coral, including the increase of sediment loading on the North Shore shipping lanes, trace metal contamination from the Castle Harbour dump, and the effect of coastal development and sewage output off the South Shore.

All hope is not lost - a BBSR statement said the Pew report concluded damage done to coral reefs by direct human activity and climate change is not totally irreversible.

Reductions of human emissions may slow global warming and improve ocean chemistry, and the regulation of pollution, development and fishing may help to insure the long-term sustainability of coral reefs, the statement said.