December 11th, 2012 by Joshua S Hill
Just to add to the worries you’ll have for New Year 2013, scientists are growing ever-more concerned with the possibility that corals could retreat from equatorial seas and oceans due to the continual warming of our planet.
An international team of marine researchers warned Tuesday that, based on the fossil coral record from the last major episode of global warming, there is likely to be 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,” Professor John Pandolfi said, Chief Investigator with the Australian Research Council Centre of Excellence for Coral Reef Studies and is Director of the Centre for Marine Science at the School of Biological Sciences, The University of Queensland.
“It appears that during this period the number of coral species present in equatorial oceans was only 50-60 per cent of the diversity found further away from the equator, and diversity was greatest in the northern hemisphere.”
The researchers found that when the sea surface temperatures warned by around 0.7 of a degree Celsius it was enough to drive many species of coral out of equatorial waters.
“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 Science.
“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,” Professor Pandolfi said.
“The answer is, increased temperatures resulted in the extirpation of many coral species in equatorial waters, leading to much poorer reef systems.”
The most worrying part of all of this? We’ve already warmed the oceans by 0.7 of a degree since the start of the industrial age, and are expected to warm them even further.
“If this is the case, it has serious implications for the nations of the Coral Triangle, such as Indonesia and the Philippines, where tens of millions of people rely upon the oceans for their livelihoods and food.”
Residents of those regions will be hard hit, given that coral is one of the great refuges for countless numbers of fish species. Take away the coral, and you’ll take away the fish as well.
“The picture that is forming is one of corals moving back and forth, towards the poles during warm periods, and retracting towards the equator in cooler times, in search of the most favourable water conditions.”
“The thought that just 0.7 of a degree of sea surface warming back then caused a 4-6 metre ocean rise is distinctly disturbing – because that is how much the Earth has already heated in the current warming episode, and the predictions are for a further one degree or more by 2050.
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