As bushfires tear through Victoria, it's worth remembering that in October last year the state's Country Fire Authority predicted that the frequency and severity of fires would increase in the future. There were also warnings from MPs, including Greens Deputy Leader Adam Bandt, who wrote on the topic at NM.
But others, including Prime Minister Tony Abbott, deny that climate change plays any part in fires, heatwaves and floods. Extreme weather they note, has always been integral to the Australian environment.
Where is the truth here? A disturbing ideological element dominates the public discourse. The political left tends to argue, seemingly almost by reflex, that climate change is a factor. The right often simply dismisses the notion that it could play a part. What is much clearer is that the land use decisions Australians have made have much to answer for.
For decades, going back to the origins of European settlement, we have been developing our floodplains by building houses, towns and suburbs on them. The transport and communications networks that bind our communities and integrate our economic activity criss-cross them. All these assets are at risk when floods occur and the damage done is costly to repair.
And since the middle of the 20th century, increasing numbers of people have built homes in areas that are prone to bushfires. Our two biggest cities have spread outwards into areas dominated by dry sclerophyll forest.
Precise figures on the numbers of dwellings in areas subject to nature's hazards are not easy to obtain. But a reasonable estimate would be that more than a million of the nine million homes in Australia are on floodplains, in areas where bush fires occur or on coasts where storm surges or erosion triggered by tropical cyclones and other intense low-pressure systems can occur.
Substantial amounts of productive activity and infrastructural assets are also exposed in such areas. Exposure is the key word here. Myriad land use decisions made by governments, companies and individuals over the decades have left us with a huge legacy of vulnerability. This has nothing to do with climate change. But the role of land use is being clouded because of the climate debate.
Where climate change may have a role is as an intensifier of the impacts of land use decisions. A trend towards higher temperatures is clearly evident globally since the Industrial Revolution, and it is possible that it is affecting the intensity, frequency, duration and time of occurrence of bushfires. That said, it is difficult to prove that such impacts have occurred to a significant degree — at least so far.
The trend towards higher temperatures does not itself cause fires. Damaged or fallen power lines, accidents, arsonists and lightning do. If rising temperatures have any influence it is on fire characteristics like severity and spread once ignition has taken place. But the critical link is difficult to establish empirically from the historical record of bushfire occurrences. Natural variability of fire conditions is more apparent than any trends that might exist in the frequency and severity of fires.
In any case, bushfires would matter much less in a human context if large numbers of people did not live and work in the kinds of areas where the most damaging fires occur — in other words if we had not already created our own vulnerability to them.
And floods? There is no clear evidence, yet, that they are becoming more frequent or more often severe. And again, they would be less consequential if people didn't inhabit floodplains in such numbers.
There was a time in Australia's history when floodplain occupation was unavoidable. Towns had to be accessible to the farmers whose needs they served and next to rivers for water and transport. Once established, the settlement pattern was largely reinforced through the inertial influence of what already existed. Urban centres on floodplains became foci of continued investment and growth — and the quantum of vulnerability increased.
Meanwhile the cities sprawled across floodplains and into bushland, and under the pressure of retirement migration (and other forms of city-escaping migration known popularly as "sea-change" and "tree-change" shifts) the population along the coast and in other areas of attraction increased. The slow emptying of inland farming areas (as farms became larger and more mechanised) intensified the trend, especially along Australia's eastern margin.
Gradually, inexorably and by dint of many small decisions, more and more people and investments became vulnerable to fire and flood as well as to storm surge and coastal erosion. None of this growth in vulnerability was created by climate change.
But if warming continues as it demonstrably has so far and as is forecast by the climate scientists, conditions will become more favourable to bushfire development and propagation. With more hot days, more evaporation and lower humidity, fire severity will increase. The losses of lives and property will grow. If "Super el Niños" become more frequent, all these things (and more severe droughts) are likely.
If the scientists are right and the extremes of drought and intense rainfall are amplified in a warmer future, there will also be larger numbers of severe floods. Rising sea levels, continuing a well established, decades-long trend, are likely to increase the frequency with which damage is done by estuarine flooding, coastal erosion and shoreline retreat: these things are already a problem in several locations along Australia's east coast. Storm surge flooding from the sea could become more common too.
We should be very wary of these possibilities, and we should be acting, to the extent we can, to minimise the foreseeable consequences of them.
In the meantime we must see land use and climate change as separate issues, and avoid concluding that climate change is fundamental to every severe weather-related disaster that befalls us. The larger culprit, so far at least, is the pattern of decisions we have made in the past and continue still to make.
We would be wise to conclude that humanity might be getting dangerously close to creating tipping points beyond which the climate itself could be substantially affected. We do not need to encourage the forces of nature to generate more intense weather that will worsen the losses we have already created for ourselves.
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