NEW projections for rising sea levels this century have reinforced a need for south-west communities to plan for a changed coast, a Warrnambool researcher says.
The Intergovernmental Panel on Climate Change predicted seas could rise up to 1.1 metres by 2100 if greenhouse gas emissions weren't curbed. The panel's prediction is up from their 2013 calculation of seas rising more than 90 centimetres.
Even if emissions were sharply reduced, seas could rise between 30 and 60 centimetres by 2100, the report also stated.
The report could prompt the Victorian government to adjust sea level rise predictions in a draft marine and coastal policy, to be finalised later this year.
Deakin University environmental scientist Dr John Sherwood said a 2014 state government strategy had planned for an 80-centimetre rise by 2100, which Warrnambool City Council adopted in its planning scheme.
"I think the council will look at that marine and coastal policy when it's released and look at their own planning scheme and see if they need to make changes," he said.
"As a community we need to be making steps early, the sad truth is it's going to be much more expensive to take steps later, acting early is the cheapest way we can deal with this."
Dr Sherwood said he was aware of evidence around Warrnambool that indicated 120,000 years ago the sea was at least six-metres higher than today, but added he had no doubt humans had accelerated climate change.
"What we are doing is putting another factor at play here, that's why we talk about man-made climate change, that's an extra dimension that is being added on top of these cycles," he said. "I can't see that any serious person should be questioning the science."
Dr Sherwood said Warrnambool was "fortunate" because most of the city was above sea level, but areas abutting rivers and estuaries could be at risk. Dr Sherwood said ecosystems that couldn't relocate inland could be worst hit.
"Along the coast we are seeing increased signs of coastal erosion, you only need to look at Warrnambool main beach and Port Fairy's East Beach over summer with sand to notice."
Moyne Shire Council planned in 2013 for a 1.2-metre sea level rise by 2100 in its coastal hazard assessment for Port Fairy, and has focused on renewing rock walls protecting East Beach. Dr Sherwood said the shire had shown leadership.
"They have been proven to be sensible planners by adopting that 1.2-metre figure. A lot of Port Fairy is on sand. Rather than transfer costs to future property owners, it makes sense to have that in the planning," he said.
Dr Sherwood said communities from Apollo Bay to Portland would increasingly look at a range of strategies to adapt.
"Maybe an artificial offshore reef to break off the wave movement, groynes, there are things we have to investigate to look at adaptation options," he said.
"We still need to be doing very local detailed studies to prepare, looking at what your options are to retreat or defend and acting on those."
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