It is common by now: Every time the weather goes crazy in one part of the world or another, bringing death and destruction through storms, floods or wildfires – such as those still raging in Australia – speculations run wild as to whether it is due to climate change. My Briefing over at Nature news has sparked another such debate.

Raging fires have caused death and destruction in Australia. Image: Punchstock

So would the extreme heat and prolonged drought that has turned the state of Victoria into a deadly tinderbox have happened even if the region hadn’t warmed by a centigrade or so over the last century? Would the record-breaking European heatwave of 2003 have been as disastrous as it has been? Would Hurricane Katrina have been able to gather such destructive power in a cooler world?

The simple answer is: We don’t know. You can’t decide in hindsight whether a discrete event – a spell of extreme summer heat in a greenhouse gas-forced climate, or, come to that, two sixes thrown with a pair of manipulated die – would or would not have happened had the probabilities not been altered beforehand.

But you can bet anything you like that uneven probabilities will have an effect on how often you throw a six. And the same applies to weather: Changing the physics of the climate system will inevitably result in more frequent atmospheric conditions X and less frequent conditions Y.

Climate change, from everything we know, will very likely increase summer heat and drought in subtropical Australia. So there is indeed every reason to believe that bushfires, although they have always been common in the region, will become more severe. And as an ever increasing number of Australians are building homes in suburban areas backing onto bushland and eucalyptus groves, the fires could become even more damaging in the future.

Urban planners must take this into account. Besides, a method called ‘prescribed burning’ – also called back-burning in Australia – offers some hope of mitigation. But, as one comment to my Briefing points out, deliberate burning of dead leaves, timber and grass is a quite controversial means of bushfire control, and has recently declined following agitation by environmental groups.

Quirin Schiermeier