There is growing scientific concern that corals could retreat from equatorial seas and oceans as the Earth continues to warm, a team of international marine researchers warned today.
Working on clues in the fossil coral record from the last major episode of global warming, the period between the last two ice ages about 125,000 years ago, the researchers found evidence of a sharp decline in coral diversity near the equator.
"When the climate warmed rapidly during the Last Interglacial, coral species diversity was much lower close to the Equator than at higher latitudes," says Professor John Pandolfi of CoECRS and The University of Queensland.
"It appears that during this period the number of coral species present in equatorial oceans was only 50-60% of the diversity found further away from the equator, and diversity was greatest in the northern hemisphere."
Professor Pandolfi and his German colleagues found that, when sea surface temperatures warmed by about 0.7 of a degree Celsius during the interglacial warm period, it was enough to drive many species of coral out of equatorial waters up to 10 degrees of latitude on either side of the equator.
"Our results suggest that the poleward range expansions of reef corals occurring with intensified global warming today may soon be followed by equatorial range retractions," the team says in their latest paper, published in the Proceedings of the US National Academy of Sciences.
"Earlier work revealed that the corals had marched as far south as Margaret River in Western Australia during the interglacial and we wanted to establish what was happening at the 'hot end' of the corals' range," Prof. Pandolfi explains.
"The answer is, increased temperatures resulted in the extirpation of many coral species in equatorial waters, leading to much poorer reef systems."
What concerns the scientists is that the planet has already warmed by 0.7 of a degree
|Contact: John Pandolfi|
ARC Centre of Excellence in Coral Reef Studies