Coral reef study raises 'catastrophe' fears

Published Date: 16 April 2009
By John von Radowitz

A WARNING that the world could be heading for a "catastrophic" rise in sea level has emerged from a study of ancient coral reefs.
The findings indicate what might happen if the Antarctic and Greenland ice sheets continue to melt at the present rate. They suggest a sudden and major rise in sea level could occur by 2100, with grave consequences for low-lying communities.Currently, the world is in an interglacial period – a period of relative warmth between ice ages – called the Holocene.To get an idea of the effects of a warming world, scientists have looked back at the last interglacial period, between 110,000 and 127,000 years ago.Although it is known that sea levels rose during this period, the speed of the change has been less clear.The new research, led by Dr Paul Blanchon, of the National Autonomous University of Mexico in Cancun, focused on two fossilised coral reefs at Xcaret on the Yucatán peninsula.A low-lying reef was killed off by an abrupt jump in sea level which occurred about 121,000 years ago, the evidence showed. It was replaced by another reef built on higher ground.Corals are famously sensitive to environmental conditions determined by depth, temperature and salinity. If sea levels rise more quickly than their slow growth can deal with, they die.The rise in sea level that killed the coral must have happened at a rate faster than 36mm per year, the findings reported in the journal Nature showed.