First published on 14 Jun 2011. Updated on 16 Jun 2011.
IMAGE: SONY PICTURES HOME ENTERTAINMENT
DR BRUCE SCHAEFER
Senior Lecturer in Earth and Planetary Sciences, Macquarie University
"Australia's surprisingly tectonically active, given that it's in the middle of a [tectonic] plate. Ours is a slightly unusual plate because it's attached to India, which is busy slamming into Asia, and the crumple zone as Australia moves north is Papua New Guinea, and that transmits stresses in an unusual way through the plate. So Sydney's as much at risk of an earthquake as Newcastle [where in December 1989 a quake reaching 5.6 on the Richter magnitude scale struck, killing 13 people and causing $4 billion in damage].
"The big thing with Australia is that none of our cities are designed for it. At least in New Zealand the town planning is such that there's a lot more awareness of it because earthquakes are commonplace, but if we had a Newcastle-scale earthquake in Sydney, we'd be in all sorts of trouble: we're not equipped for even a modest-sized earthquake. Certainly things like the Harbour Bridge were not designed with earthquakes in mind, for example. [Australian] councils don't require people building stuff to pay much attention to earthquake-proofing, so a smaller earthquake could do more damage in Australia than quite a large one in New Zealand."
Research Director and Deputy CEO, Bushfire Cooperative Research Centre
"Australia has always had fire as a part of its natural ecosystem - in fact eucalypts must have fire to survive. So fire risk is an annual thing. The recent wet season doesn't mean the risk goes away: in fact it's made worse because rain causes things to grow. Sydney is one of the major hotspots in terms of fire risk, being surrounded by national parks. Sydney's had its share of big fires. The 2001 Christmas Fires came close to the central suburbs. That can always happen again.
"Houses are mostly lost due to ember attack rather than direct flame. You could be three streets back from bush and still get ember attacks. Even if you're right in the middle of a suburb, if you have any bush around you you've got a bushfire risk. The fires in 2001 came very close into the centre of Sydney because there are corridors of vegetation.
"What we found through the Royal Commission is that it's not good enough to be physically prepared - reducing fuels surrounding the house, et cetera - but individuals have to be psychologically aware of what it is they're about to face if they're preparing to defend. It's important for residents understand when to stay and defend and when to leave early. It's important for people to know where to go for information and the NSW Rural Fire Service is the primary one for bushfire. Fire and Rescue NSW also have information on assessing risk."
PROFESSOR ANDY PITMAN
Director, ARC Centre of Excellence for Climate System Science, UNSW
"In the Sydney region, the chances of severe heatwave - hotter days and warmer nights - increases significantly as we warm the planet. People say ‘global warming is three degrees, who gives a damn?' What they don't understand is that if we currently have three days at 40°, the way that works is you would then probably get at five days at 45°, and that really hurts.
"People always think global warming will happen ‘in the future'. But remember this summer just gone? That week of warm and humid nights? We are observing the impact of global warming every year now. We're very much the frog in the saucepan and the saucepan is already being warmed up. We're not very good at responding to gradual changes no matter how serious.
"Assuming Sydney plans for future climates - and that's a big assumption - we can adapt to much of the changes. There's a range of things we can do. Those beautiful old Federation houses stay cool in summer without air conditioning. The worst thing you can build is a McMansion with a tarmacked area around it. That's exactly what's being built out in Western Sydney, so what you get is known as the urban heat island effect - which can be quite a few degrees on top of global warming. Western Sydney is much more vulnerable to climate change because it tends not to get sea breezes, so that's a double whammy."
DR HELEN JOHNSTON
Research Fellow, School of Physics, University of Sydney
"Solar flares are basically explosions on the surface of the sun. The sun's magnetic field gets twisted up and these giant explosions release all that energy as anything from xrays to radio waves - the whole electromagnetic spectrum is emitted by these flares. Now, the Earth's magnetic field protects us from much of this, but the largest events can overwhelm it - and those are the ones that everyone's worried about.
"It'd be like a giant lightning strike in some ways: you basically get electric currents induced in the atmosphere, which then overload all the circuit breakers on a power network. In 1989 there was a solar storm that knocked out the whole of the electrical grid in Quebec, leaving nine million people without power in the middle of winter. And x-rays from solar storms have interrupted GPS navigation, and all the electronics in satellites can be fried: all in all, it's not particularly pleasant. We're more and more susceptible to these things [these days] because there's so much that's electronic that we depend on now, and most just cannot handle that much current going dumped into it.
"There are several new satellites up now observing the Sun continuously, so we'd get some hours warning of an event, but of course, we're coming up to solar maximum in the next year or two, so the number of these flares will be going up..."
APOCALYPSE SYDNEY PART 2
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