SPEAKING as part of the UWA Oceans Institute Dialogue Series, Dr Robert J Nicholls warns a one-metre rise in sea levels could have as great an impact on coastlines as fast onset disasters such as a tsunami.
While the University of Southampton Visiting Fellow would like more international cooperation on climate change, mitigation’s impact on the oceans would be limited.
“Mitigation will reduce and delay sea level rise, but some climate-induced sea level rise will occur irrespective of future emissions,” he says.
“The ocean has the lowest response to mitigation of any part of the climate system, because only the top of the ocean has seen the recent warming.
“The bulk of the ocean still has to warm in response to that change, and that will lead to thermal expansion, so this process just keeps on going.”
This was termed the ‘commitment to sea level rise’ by the UN Framework on Climate Change.
While coastal protection is daunting, Dr Nicholls sees it as the only option, noting London and Amsterdam are already creating safeguards against four to five metre scenarios.
“About 85% of the world’s coast should be protected, reflecting the fact the coast has high value,” he says.
“Protection isn’t actually terribly expensive compared to those values in a cost-benefit sense, so it’s an option that should be on the table when we evaluate decisions.”
He says even if no action were taken until 2025, when costs could be 100 times greater, protecting one-third of the coast would make sense.
While not as vulnerable as South and Southeast Asia and Africa, Australia still needs solid coastal management.
WA gets a mixed review.
“Your current policies of building on the open coast already do think about sea level rise,” says Dr Nicholls.
“There is a lot of thought about erosion—expressed by building setbacks—but less so on flooding, particularly away from the open coast.”
In particular, he notes Rockingham, echoing the Australian Government’s 2009 Climate Change Risk to Australia’s Coast (CCRAC) which lists the area as one of four at highest risk of sea level rise inundation.
The others are Busselton, Mandurah and Bunbury.
Overall, the CCRAC estimates between 18,700 and 28,900 residential buildings in WA to be at risk from a 1.1 metre sea rise, representing $4.9 billion to 7.7 billion
Yet Dr Nicholls is optimistic.
“Climate-induced sea level is inevitable, and the do-nothing impacts are significant, but there is time to respond if we start now.”