Perfect storm could devastate Coast
Sat 15 November 2008
Rhiannon Oakley, Bachelor of Communication (Journalism)
Climate change may bring tropical cyclones as far south as the New South Wales border, placing Sunshine Coast properties at risk from wind damage, flooding and storm surges.
South-East Queensland was identified by the Intergovernmental Panel on Climate Change (IPCC) as one of Australia and New Zealand’s six key “hot spots” likely to be highly vulnerable to climate change.
The Queensland Government Office of Climate Change released a report this year detailing how climate change could affect Queensland.
Using climate models and emission scenarios, the scientists predicted three possible routes climate change could take in the future, depending on how far greenhouse gas emissions could be reduced.
“Ongoing development is likely to be exacerbated by large losses to built environment from rising sea level, storm surges and flooding,” the report said.
One-in-100 year storm tide events have been projected to increase by 0.45m along the Sunshine Coast because of mean sea level rises.
The report said potential impacts of climate change could include “an increase in extreme daily rainfall, sea level rises, more intense tropical cyclones and an increased risk of storm surge”.
Because future rainfall is difficult to predict and depends on general conditions in the atmosphere, scientists have not reached a consensus on whether rainfall is likely to increase or decrease.
Some have said while tropical cyclones are likely to be more intense the frequency of the cyclones may decrease.
However, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) reported an increase in the number of severe tropical cyclones in 2007.
Bureau of Meteorology Queensland manager of weather services Ann Farrell said cyclones could affect South-East Queensland, even though it is a rare occurance, and that it would be hard to predict whether the Sunshine Coast would be affected until a system had already developed.
“We can’t really predict longer range than in the next week or so,” Ms Farrell said.
Ms Farrell added that low-pressure systems can also have a significant impact, causing flooding, wind damage and storm surge.
University of the Sunshine Coast senior lecturer and former Cape Grim Baseline Air Pollution Station officer Neil Tindale explained why the Sunshine Coast may see a tropical cyclone.
Dr Tindale said previously the approximate area for tropical cyclones was thought to be north of the Hervey Bay region, but is now thought to have moved south towards the New South Wales border.
He explained that pools of warm water fuel tropical cyclones, meaning cyclonic weather activity could be predicted from the La Nina and El Nino weather trends.
During La Nina conditions, the warmer waters of the Pacific Ocean drift west towards northern Australia.
Dr Tindale said these warmer waters then provide the required conditions for a tropical cyclone (water 26C to a depth of at least 50m).
The Bureau of Meteorology forecasted in the coming tropical cyclone season a mild bias towards La Nina conditions.
If a tropical cyclone were to cross land over the Sunshine Coast, the area would be at risk from wind damage, flooding and storm surges.
A storm surge is a mound of water created by strong winds that then push the mound onto shore.
Dr Tindale said storm surges were different to tidal waves or tsunamis.
“It comes in like a very fast tide,” Dr Tindale said.
Tropical Cyclone Larry in 2006 produced a storm surge of 2.3m, with waters reaching 4.9m above expected tide levels at Bingil Bay.
The same situation could be potentially very dangerous for the Sunshine Coast, with much of the population living right near the water.
Dr Tindale said that, as much of the Sunshine Coast is 3m above mean sea level, if tides reached 4.9m above expected tide levels a large area would be inundated with water more than 1m deep.
However tropical cyclones have been known to hit South-East Queensland in the past, before most people became aware of climate change.
A tropical cyclone crossed the coast at Coolangatta on the New South Wales border in 1954, with intense rainfall and winds damaging the coast between the Gold Coast and Sunshine Coast.
In 1974 Cyclone Wanda crossed the coast near Fraser Island.
While there was little wind damage, the accompanying barrage of rain caused major flooding in South-East Queensland.
In preparation for climate change related impacts, the Sunshine Coast Regional Council published its report on storm tide management this year.
The report recommended that the one-in-100 year storm tide level should be the limit for development and that there should be a buffer zone allowing for wave run-up at coastal sites, plus an extra 0.5m elevation for new flooring in buildings to allow for mean sea level rise associated with climate change.
Image(s) designed by Rhiannon Oakley