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May 23, 2011
Australia's Climate Commission has just released its The Critical Decade is an update on what natural science is now telling us about climate change, and with regard to the underpinning it provides for the formulation of policy and the risks of a changing climate to Australia.
As Alan Kohler points out a key problem that Australia must solve is the use of brown coal in generating electricity. Around 79 per cent of the power sold into the National Electricity Market comes from burning coal and 27 per cent from brown coal. The brown coal alone produces 72 million tonnes of carbon dioxide, which is 13 per cent of the nation's emissions. At the barest minimum brown coal power generation needs to be phrased out.
My interest in the risks of a changing climate to Australia is with the rising sea levels. The report estimates these to rise to 2100 from 2000 to be 0.5 to 1.0 m, though it acknowledges there is significant uncertainty here due to the dynamics of large polar ice sheets, which are currently not well understood.
However, the report states that:
the impacts of rising sea-level are experienced through “high sea-level events” when a combination of sea-level rise, a high tide and a storm surge or excessive run-off trigger an inundation event. Very modest rises in sea-level, for example, 50 cm, can lead to very high multiplying factors – sometimes 100 times or more – in the frequency of occurrence of high sea-level events.
High sea level events are defined as high tides and storm surges and the risks are greater for inundation events, which damage human settlements and infrastructure in low-lying coastal areas, and can lead to erosion of sandy beaches and soft coastlines.
Various scenarios have been modelled by the Department of Climate Change and Efficiency.
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Of all the capitol cities Sydney is going to be the most badly affected by rising sea levels, then Melbourne and Brisbane.