Ready for heavy weather

Age
Monday 21/4/2008 Page: 13

As weather patterns turn more volatile, we need to climate-proof our cities, writes Peter Fisher.
EVEN the mild autumn days we're enjoying, it is easy to forget that almost three weeks ago Melbourne was battered by storms that not only caused property damage and a great deal of personal inconvenience but, more importantly, resulted in two deaths. These storms show that climate change need not be a gradual, creeping, almost benign process - balmy winters, growing acidity, water shortages, that sort of thing - but is capable of turning very nasty.

The damage and disruption to Melbourne's urban fabric - houses and commercial buildings, train lines, roads, power networks, even losses to our tree canopy - as well as the loss of human life, have demonstrated that the city needs to be better prepared against such ravages, which Premier John Brumby has conceded will "happen more often" under climate change.

Change is already locked into the global weather system. So in addition to trying to limit carbon emissions by renewable energy and clean coal, we should also be developing means to more adequately manage the effects of climate change, to minimise risks from cyclonic-force winds, deluges, blistering heat waves (such as that visited on Adelaide last month), bushfires and sea-level rise.

Residents still have little to guide them in their choice of housing or building locations. Vast numbers are living and working in susceptible localities. Low-lying flood-prone areas, waterfronts, land likely to slip and perhaps areas liable to strong wind or bushfire are clear concerns. The insurance industry is acutely aware of these risks and in the future will reflect them in higher premiums or a refusal to insure, as already happens with seafront properties in Florida often hit by hurricanes.

While the building industry is researching stronger materials to protect against things such as large hail damage, retrofit programs are needed, especially in more densely settled areas, to guard against heat stress (which killed thousands of elderly people in the Paris heat wave of August 2003), retain run-off from heavy rain and direct high winds away from high population areas. Trees can be strategically used, especially for cooling, with the added bonus of carbon sequestration, provided these are species that are less prone to limb fall. Hard surface coverage and reflective glass should be reduced and other heat absorbing and radiating exteriors limited.

Victoria's building requirements have recently been revised to include five-star energy provisions, but do not incorporate adaptation to weather extremes. For example, there are no stipulations barring box spoutings between joined buildings, which have a tendency to overload and allow water to seep between walls. Houses without eaves, even though frowned on by the Planning Appeals Tribunal, can still be built, and stipulations about surfaces being able to readily absorb stormwater are patchy and spread across many levels of planning jurisdiction.

The Rudd Government's recently announced $15 million Climate Change Adaptation Research networks should help define how many of these issues are to be tackled in the Australian building code. With the state's key infrastructure, we should plan to counter low-risk, high-impact events such as the destruction of the Thomson, our largest water catchment, by bushfire. With winds like those we have just experienced, the best buffer zone in the world could not keep a fire out of the watershed. Once fire had broken through, there would be contamination of dam water and a lowered yield as thirsty mountain ash saplings soak up run-off for a decade or more.

Melbourne proposes to insulate itself against such a supply emergency by building a large desalination plant. But will this solve the problem? These plants, located close to the shoreline, could be flooded in decades to come as sea levels rise from melting ice sheets in Greenland and western Antarctica or by a storm surge through a combination of high tide, torrential rain and gale force winds increasing wave heights under the influence of an intense low-pressure system. This is not the working of an overactive imagination. A storm surge destroyed the clubhouse of the Sea Spray Surf Life Saving Club last June. The rest of the structure fell into the sea a few days later.

It is vital that storm surge and sea-level rise are factored into the placement and modelling of desalination plants. A few weeks ago the Wilke Ice Shelf suddenly lost a large chunk. It lies just five degrees north of the western Antarctic ice sheet, which rests on rock below sea level. Should this disintegrate, global sea levels would rise by five metres. Described by one climatologist as an "awakening giant", the western Antarctica ice sheet should be on the whiteboards of all water planners.

Meteorologists have predicted that cyclones will track further south in the future. But Melbourne's recent storm came from an unexpected quarter - tropical cyclone Pancho, which descended from the Kimberley coast and combined with a cold, low-pressure system in the bight before heading west. While Sydney periodically experiences highly damaging stomas, Melbourne has been relatively immune from such disturbances. If this is about to change, many power lines will need to go underground.

If, as the science suggests, there is a connection between climate change in full swing and extremes in weather patterns, we should not only be thinking about the security of future city water supplies or drought at large. An early start needs to be made on "climate-proofing" our city as it takes time to change buildings, redesign infrastructure and establish coastal setbacks. The longer we delay, the harder it will get.

Dr Peter Fisher is an environment management consultant. He co-ordinated a climate change risk assessment - one of the first in Australia - commissioned by City of Port Phillip council.