Global warming and the NSW floods

June 16, 2007

The recent storms that devastated much of the NSW Central Coast and the Hunter Valley were described by some as a mini cyclone. The fierce gales led to dramatic floods — the most severe since the 1970s, the deaths of several people and the beaching of a coal freighter on a Newcastle reef.

In Maitland, residents were evacuated from their homes for fear that rising flood waters would breach the levies. The floods cut electricity for thousands of Hunter Valley residents and 11 people lost their lives, including a family whose car came off the road when a section of the Old Pacific Highway at Somersby was washed away.

The coal freighter Pasha Bulker was one of many ships that line up outside the harbour. At any time, day or night, you can see at least five of these massive vessels from the Newcastle beach. They line up because the harbour is quite narrow and only two specialised coal loaders are available for use.

They also line up because Newcastle is the biggest coal port in the world. More coal is transported through this port — both local coal and that from mines across Australia — than any other port in the world. But the storm has halted all coal loading, causing an estimated 2 million tonnes of lost exports, according to a June 14 News Limited report. The June 13 Sydney Morning Herald estimated that the cost to the coal industry in exports would be $115 million.

The 40,000-tonne Pasha Bulker was buffeted by the strong winds and driven onto the beach while waiting to load up coal for export. Its break up could cause a marine disaster.

The storm arose from the shift from the El Nino to the La Nina weather pattern. This shift was a lot fiercer than previous shifts.

A July 2006 article titled "Droughts and Flooding Rain" on the ABC Scribbly Gum science website analysed the effects of climate change on global weather patterns. It said that the impacts of the enhanced greenhouse effect on El Nino are not likely to be straightforward and will depend on how fast, and by how much, the Earth warms.

Dr David Jones, head of climate analysis at the Australian Bureau of Meteorology, predicted in the article that El Nino droughts will be hotter and La Nina rains heavier. Cyclones may increase in intensity and spread further south. He also said it is likely that fire regimes will also change, although to what extent is unknown.

"Essentially the [climate] response to climate change is quite uncertain", he warned. "If you nudge a system you cannot always predict the consequences. A small nudge may lead to a small change in the behaviour of El Nino, while a bigger nudge may well change the nature of El Nino altogether." The 2006 report implies that an event of this magnitude was likely to occur when the La Nina cycle began. But no-one seems to have restated this fact since the storm.

While this doesn't make climate change directly responsible for the damage wreaked in NSW by the storms, it does mean that climate change may have made the weather shift more sudden than it would have been otherwise, and it may make the next storm even more severe.

While governments and corporations continue to pursue coal profits despite overwhelming evidence that carbon emissions contribute to runaway climate change, we can expect more such violent weather events.

It's more than a little ironic that this latest episode of wild weather ensued a day or so after the NSW government announced it would approve the contentious Anvil Hill coalmine. The mining and burning of coal is responsible for 40% of Australia's greenhouse gas emissions. NSW Greens MLC Lee Rhiannon estimates that the Anvil Hill mine will add more than 500 million tonnes of CO2 to the atmosphere during its operational life.

While scientists are not linking the storm directly to carbon emissions, climate scientists do agree that emitting more CO2 into the atmosphere will increase the chances of extreme weather events — another reason to move to renewable energy.

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