What if Hurricane Sandy came to Sydney?

The Infrastructure NSW people have come out with what I think are sensible warnings about the possibility of huge storms in the future and what might be done to anticipate them — including raising the height of Warragamba Dam. Sydney seems to generate its own weather — I remember that when sailing on Sydney Harbour in the 1970s — but we do not seem to have the frequency or the intensity of the hurricanes that sweep into the eastern USA from the Atlantic, and have done so since settlers began to write about them a few hundred years ago.

I have mentioned the work of Roger Pielke Jnr before, and he has done his best to put Hurricane Sandy into historic perspective, in an article in the Wall Street Journal. One thing that has not been mentioned much in the news reports is the relatively low loss of life from the storm, which Pielke attributes to the weather forecasting of the US National Weather Service, plus the efforts that are now made to be prepared for extreme events and respond quickly to them.

I think the same is true in Australia. there has been a great increase in the role of Emergency Services in the last decade or two, and we are getting much better at anticipating fires and floods and responding to them early. I feel that we have had in the past a somewhat complacent feeling that the earth is stable and supportive, and that severe storms and floods are unexpected and somehow wrong. Today the feeling is growing that these unpleasant weather events are part of the natural order of things, and that we had better be ready to deal with them. That is in every way a more sensible approach.

Pielke’s view of Sandy is that it was nothing out of the ordinary, nowhere near as bad, in terms of its normalised cost, as Hurricane Katrina that devastated New Orleans in 2005, which was one of the strongest storms ever to hit the USA. And there have been stronger storms closer to New York in the past, including three in the mid 1950s, each of which would have been twice as destructive as Sandy.

The grandaddy of them all, it seems, was one in 1821 which raised the water level in the Hudson about as much as Sandy did. But that storm surge occurred at low tide, there was no full moon, and the seas in 1821 were about 25 cm lower than they are today. Had the Sandy conditions existed, it would have surpassed Sandy by far in its destructive effect.

Pielke and others have also pointed out that there are fewer hurricanes about now than in the past, the seven years that have passed since Hurricane Wilma made landfall in 2005 making the ‘drought’ of hurricanes hitting the eastern seaboard the longest such period for a century. The cost of flood damage in the USA has also decreased, as has the incidence of floods. I mentioned in an earlier post Pielke’s assessment that historic tornado damage, and deaths from these storms, have also declined.

These assessments sit oddly with the scary talk both here, from our Climate Commission, and in the USA that weather events like Sandy are now ‘the new normal’. On the evidence the reverse is true, at least in the USA: it is, for some reason, in a rather calm period. Some put it down to increased warming, because they can point to truly horrific storms in the 17th century, when the northern hemisphere was in the grip of the Little Ice Age. Given the spottiness of the data and the lack of really good understanding of what drives climatic shifts, one needs to suspend judgment.

But there are things that we can do. Here’s a question posed by Roger Pielke Jnr (whose work seems to me to be the sanest I have read in this area):

‘So how can today’s disasters, even if less physically powerful than previous ones, have such staggering financial costs? One reason: There are more people and more wealth in harm’s way. Partly this is due to local land-use policies, partly to incentives such as government-subsidized insurance, but mostly to the simple fact that people like being on the coast and near rivers.’

It is as true of Australia as it is of the USA. The message is: don’t build houses where you might be flooded. If you do, don’t expect everyone else to pick up the tab for you if a flood occurs. And for local government councils: don’t allow building on flood plains or areas where there is evidence of past floods — no matter what the developers tell you, or the short-term profits you will make from new construction. It’s not worth it in the long run.



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