( rish and reefs to form. The discovery i...)Reef warns of sea level rise

rish and reefs to form. The discovery is of particular importance as it shows that sea levels rose not only because of the expansion of the oceans due to warming, which can account for ~1/2 metre of sea level rise, but also because it indicates that relatively large scale melting of landbased icesheets occurred in Greenland or the Antarctic. It is the very rapid rise in sea level from catastrophic melting of landbased icesheets where there the greatest uncertainty and concern lies. Now from the Margaret River corals we have evidence of not only unusually warm ocean temperatures, but that that this was associated with rapid melting of icesheets contributing to an additional 3 to 4 metres of sea level rise. "

The cause of the sudden global warming leading to the end of the ice-ages is thought to be due to changes in the elliptical nature of the Earth's orbit combining with other factors, such as variations in its tilt or wobble. During the ice ages atmospheric CO2 was around 180 parts per million, compared to 280 parts per million during interglacials. We don't know quite why CO2 levels rose so much during the last interglacial, but it may have been partly due to a reduction in the ocean's ability to take up atmospheric carbon, as the seas warmed.

Today CO2 levels are even higher, at 380 parts per million with the additional 100 ppm being mainly due to human activities. Prof. McCulloch says the oceans currently removed around 40 per cent of the anthropogenic CO2 from the atmosphere and it would be a matter of concern if their ability to do this decreased under global warming. If levels continue to increase, to above 500 ?600 parts per million as many scientists expect to be the case by 2050, then the climate shifts and warming effects and will become even more dramatic and surpass those of the Last Interglacial warm period"

"Sea level rises and falls have occurred throughout geological history and are all slightly different from one
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Source:James Cook University

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