Australasian Science: Australia's authority on science since 1938

Ancient Sea Levels Surged

By Stephen Luntz

Sea levels experienced a dramatic surge during the Earth’s last warm period, spelling a warning about what could soon be in store for the world.

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“During the last interglacial there was an extended period where sea levels were 3–4 metres higher than today, with climate a little warmer,” says Dr Mick O’Leary of Curtin University’s Department of Environment and Agriculture. “At the end of that period they suddenly jumped to 8.5 metres.”

O’Leary says measurements are not precise enough to determine the period over which this happened: “It could have been 1000 years, but it could have been less than 100”. He hopes better techniques for dating fossil corals will answer this question.

“During the first part of the interglacial the Northern Hemisphere was receiving more sunlight than now. We think Greenland’s ice cap was reduced, and this explains the 3–4 metre rise,” O’Leary says. “At the end, the insolation curve shifted and the majority of the heat moved to the Southern Hemisphere, which we think melted the West Antarctic ice sheet.”

The West Antarctic ice sheet is considered more unstable than its larger neighbour on the east of the continent, as it is grounded below sea level and thus a more likely source for most of the sea level rise.

Although similar patterns for sea level rise have been observed elsewhere, these have been subject to considerable dispute. “While global temperatures and CO2 levels are fairly well-understood for the last interglacial period, the level of the sea during...

The full text of this article can be purchased from Informit.