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Sandy has lessons for Australia, BoM says

Australian atmospheric scientists and the Bureau of Meteorology are closely monitoring Post-Tropical Cyclone Sandy for what it tells them about climate risks in our own region - and the best way to communicate the dangers to the general population.

“Everybody's tracking it here closely,” said Karl Braganza, manager of climate monitoring at the Bureau of Meteorology's National Climate Centre in Melbourne.

Sea-surface temperatures in the Atlantic region when Hurricane Sandy - since downgraded - formed were between 3 to 5 degrees Celsius higher than average levels, helping to increase the storm's ferocity as it joined other storm systems to batter the north-eastern United States.

Scientists are reluctant to attribute any single weather event to the effects of global warming. Climate models, though, predict fewer – but more intense - major storms such as cyclones or hurricanes.

“This is the sort of thing we're warning about increasing over time,” Dr Braganza said. “We are breaking records across metrics where we'd expect to break records as the planet warms.”

The bureau's scientists are also interested in the period of very unusual pressure patterns over North America since the start of summer, notable for its extreme heat and the worst drought in many regions for decades. Some speculate that the extraordinary weather patterns may be linked to the record sea-ice melt across the Arctic that smashed records, Dr Braganza said.

Tidal data at The Battery on New York's Manhattan Island, meanwhile, hit a record 14 feet (4.3 metres) above average levels before easing back to 12 feet, according to a live reading on the US National Oceanic and Atmospheric Administration's website. That compares with a predicted peak of nine feet, Dr Braganza said.

The Bureau of Meteorology has compared Hurricane Sandy to Cyclone Yasi, a monster storm which slammed into Queensland in February 2011. For instance, Yasi's peak winds averaged 205 kilometres an hour, more than Sandy's 150 km/hour.

Yasi's storm surge reached 5.33 metres while Sandy's forecast was for 3.3 metres and apparently exceeded. The length of coastline affected by hurricane-force winds has been longer for Sandy at 350km compared with Yasi's 130km coastal range.

Flood risks

Dr Will Steffen, a member of the Australian Climate Commission, noted that Sandy is only a category 1 hurricane, but the damage will likely be significant because of its huge size and the fact that its landing coincided with a high tide.

“Sea-level rises - the observed sea-level rise around the world over the past century, and the projections for further rises - are related to climate change,” Dr Steffen said.

“It is the combination of sea-level rise, storm surge (like the one coming in from Sandy on the eastern USA coast) and high tides that lead to the worst flooding events.”

“The point here is that even modest rises in sea-level - of just tens of centimetres - can lead to much higher probabilities of high sea-level events,” Dr Steffen said.

Australian states offer a mix of estimates of how far sea levels will rise in the future. Western Australia, for instance, tips a 38cm rise by 2100 and South Australia forecasts 1 metre, according to a report out yesterday from the Climate Institute. Tasmania doesn't give a forecast and the New South Wales government has recently dropped any land-use benchmarks related to sea-level rises.

Lessons

The Bureau of Meteorology is also studying the effectiveness of US government public alerts ahead of Hurricane Sandy's arrival and how receptive the population has been as a guide to how to handle future disaster risks in Australia.

“We've been most interested in the warnings that have been put out by the US agencies,” said the bureau's Dr Braganza.

However, getting the broader message through that authorities everywhere need to consider the increased risk to lives and infrastructure from a warming climate is an issue that is likely to linger well after the storm event, he said.

Hurricane Irene left a damage bill of as much as $US20 billion when it swept across the eastern US seaboard in August 2011, Reuters cited economist Peter Morici at the University of Maryland as saying.

Sandy will cause about $US35 billion to $US45 billion in losses and damages but then be followed by as much as $US36 billion in recovery spending, Professor Morici said.

“It's that sort of vulnerability and risk that we're trying to communicate,” he said.

With Reuters

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