[author]Simeon Michaels[/author]
If a new book is to be believed, the east coast of Australia could be in for some turbulent times, not only because of global warming but also because of a little-known long-term influence over our climate.
Storm damage and coastal erosion are hotly debated topics and while opinions abound, few of the historical facts are known.
Here are just a few: since first surveyed in 1828, Byron Shire’s beachfronts have moved roughly 350 metres further inland. Roads and railways have been swallowed by the sea.
Standing atop Cape Byron in the 1800s, one could see a sand spit extending out from Little Wategos almost a third of the way to Julian Rocks. Further inland, the majority of what is now Byron’s CBD was simply marked ‘swamp’.
It’s all part of a study by local resident and one of Australia’s leading storm researchers, Dr Peter Helman.
Dr Helman’s doctoral research is entitled Severe Storms on the East Coast of Australia 1788–2008. It’s the fruits of three years of labour and details every documented instance of severe weather to hit the east coast of mainland Australia.
230 years of data
In 230 years of storm data, Dr Helman began to see a pattern.
With some exceptions, he claims the period since European settlement has witnessed a series of 20–30-year phases of severe storm activity, followed by 20–30 years of relatively calm, dry weather.
In high-energy periods, the coastline was devastated by severe storms. In the calm years that followed, the coastline gradually recovered as sand returned to the shores.
Is there a scientific explanation for this cycle? The Southern Oscillation Index (SOI), aka the El Nino effect, is measured by the difference in temperature across the Pacific.
Its effects on weather are well understood, but it is a two- to seven-year cycle, and doesn’t explain the longer-term trends that Dr Helman observed.
In 1997, however, Steven R Hare noticed the Inter-decadal Pacific Oscillation (IPO). It measures a temperature rise across the entire Pacific.
It’s a 20–30-year cycle, which may provide an explanation for Helman’s storm cycles.
Says Dr Helman, ‘When the entire Pacific warms, two things happen. Firstly, cyclones get their energy from heat on the sea surface, so we get more storms. Secondly, water expands when heated, so higher sea temperatures also mean higher sea levels.
‘This is a double whammy – bigger storms, and when they come ashore, they have a lot more water behind them.’
Helman believes this cycle started in the 1860s.
When the peak of the IPO cycle coincided with a strong La Nina episode, the result was ‘The Storm Year’ of 1864.
In that year, two tropical cyclones and eight severe winter storms wrecked 43 ships, washed away the Stone Jetty at Cleveland Point and saw the Mary River burst 8.2 metres over its banks.
It was also the storm that gave Tallow Beach its name, as ‘Schooner Volunteer capsized and was blown onto rocks… 114 casks of tallow were strewn across beach south and north of Cape Byron’.
This freaky period continued to 1866, with one of the biggest storms ever recorded raging from Elliot Island to southern Victoria, wrecking 35 ships.
The result of these devastating years was neatly summarised in police records of 1864.
‘Constable Henderson travelled from Ballina to Tweed with ‘not a single habitation to be seen at or near Byron Bay’.
When the IPO crossed into its cool phase in 1895, a period of general coastal calm followed, while inland, rains failed in the federation and WWI droughts.
Bucking the trend, 1899 saw the only category-five storm ever recorded on the east coast, causing 350 fatalities.
The IPO’s warm cycle between 1908 and the early 1920s never really got cooking, though it did dish up an east coast low in 1921 which swept SS Wollongbar up onto the beach.
As a result of anomalous events such as these, a raging scientific controversy surrounds the IPO: Why do temperatures in the Pacific oscillate? Is the phenomenon connected to, or distinct from, the El Nino cycle? Is the IPO relevant to forecasting at all?
The most recent warm phase in the IPO began in 1945 with double peaks in the mid 50s and 70s. In this phase the local correlation between the IPO and severe storms is at its strongest.
In February 1954, a severe tropical cyclone left its usual habitat in northern Queensland and headed south.
Coming ashore at the Gold Coast, the storm deposited boats in tree-tops and buried the highway at Kirra under two metres of water before heading south. The storm’s eye sat over the Condong sugar mill north of Murwillumbah for two hours before smacking Lismore. Springbrook received 900mm of rain in 24 hours.
Houses were blown apart at Cudgen. Lismore flood waters were 11km wide. The outer 180m was knocked off the Byron Jetty. Twenty-eight people lost their lives. It was ‘the worst storm in living memory’.
In 1974, during the second peak of the IPO cycle, storms tore chunks out of the coastline, including the carpark and surf club at Main Beach, while 20 housing lots were washed away near New Brighton.
In 1978, the IPO changed phase back into a 30-year cool cycle. Byron has enjoyed relatively calm, sunny conditions ever since.
This, says Dr Helman, is the core of the problem. ‘If you’re a fisherman, farmer or property developer, 30 years is your career. Our entire picture of this coastline has been formed while the IPO has been in a low-energy cycle.’
Some would see Dr Helman’s research as support for constructing breakwalls in front of storm-endangered property. According to Dr Helman, this is nonsense.
‘You can’t just choose to protect certain properties because the people there are most vocal. A storm that takes houses at Belongil will do similar damage at Lennox Head, Suffolk Park, New Brighton and all down the east coast.
Image: Pictured is the Wollongbar II in 1924 from Peter Duke’s book, Byron Bay: The History, Beauty and Spirit, which is available at www.byronbaybook.com. The Wreck is the remains of the SS Wollongbar, which ran aground in severe storms in 1921.s not returned to the coast. This is because of climate change.’
The IPO crossed over into its high-energy phase in 2006.
