Professor Lambeck started by showing a rock platform a metre above sea level from 6 thousand years ago. On Orpheus Island fossil coral is dated at 5,000 years 1 metre above current sea level and 4,000 years on Lizard Island. In contrast in the Mediterranean ancient fish tanks underwater indicate the sea level has been rising over the last few thousand years. Similarly in Bonaparte Gulf 21,280 years ago 120 metres below the present. He then took us on a fascinating world tour with a few equations up to the present.
Climate Change has been with the planet since the time of the formation of the oceans and atmosphere and is recorded, albeit imperfectly, in the geological record.
One of these records is the change in sea level through time, a complex variable that contains implicit information not only on climate but also on the tectonic and geological evolution of the planet. He will address aspects of the underpinning science and what we can learn from it, focussing on the best-known part of the record, that for the last glacial cycle.
The modern instrumental record is much more precise and has higher resolution but will also contain in addition to the `natural' variability any new signals that may result from human impact on climate. The challenge is to separate these "natural" and "anthropogenic" forcings if forecasts of future change are to be meaningful.
The problems encountered are similar to all other indicators of climate change – of separating natural and human forcing from instrumental and geological or historical records when the length of the latter are about the same as the time that human impacts may have been effective.
Professor Lambeck will use the sea level record as an illustration of many of the issues that need to be understood for a meaningful interpretation of the evidence. In so doing he will raise the role of the IPCC and where the IPCC findings are tracking in 2009; and how the public debate on climate change appears to be becoming increasingly confused while the underpinning science is becoming more robust.
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