Lessons from the blaze
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
Comments
"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, I'm quite disappointed in you for repeating this likely canard from a well-known denialist blogger. Looking at the source material (the Oz story quoting a single fire expert and a six year old letter from an individual), the former blaming "greens" in the vaguest possible manner and the latter asserting in part that firefighters have been infiltrated by greens(!), the evidence seems thin. Also bear in mind the general anti-green stance of the Oz.
I have no idea what the history is in Victoria, but based on my first-hand knowledge of similar circumstances in California, greens favor controlled burns and oppose new residential construction adjacent to wildlands, and it's real estate development interests and the homeowners themselves who create the problem. The upshot is that the presence of development adjacent to wildlands degrades them even while property values are enhanced by allowing the wildlands perimeter to intermingle with the development. Under such conditions controlled burns are going to reault in the loss of structures in addition to removing the value-enhancing vegetation, in consequence of which homeowners, developers amd the real estate industry organize against the burns and vegetation reduction.
Do such people frame their views partly in terms of respect for nature and "green values"? Sure, but that doesn't make them greens.
As they say in the journalism biz, following the money is the surest path to the real story.
Posted by: Steve Bloom | February 11, 2009 09:12 PM
Firstly I thought that regional climate forecasts were not considered reliable. Secondly I thought global warming was meant to increase precipitation.
Do you have a source for your claim that drought will increase in subtropical Australia?
Posted by: Bishop Hill | February 11, 2009 09:43 PM
You can, however, make informed comments about how much the probabilities have been altered by climate change over the last 50 years, say, and I'm a bit disappointed not to see such comments in this article.
Posted by: Mark | February 11, 2009 11:06 PM
Quirin, I don't think this approach is too much usefull .
"Would the record-breaking European heatwave of 2003 have been as disastrous as it has been?"
I am sure You know the study Stott et al. 2004 (Nature) and the graph is here:
http://bravenewclimate.files.wordpress.com/2009/02/euroheatwavereturn.jpg - the graph and the paper says the probability of the heatwaves in Europy ALREADY doubled, so climate change is NOW and we KNOW it.
The same with wildfires, let me allow to quote from prof. Barry Brook blog:
http://bravenewclimate.com/2009/02/10/heatwave-update-and-open-letter-to-the-pm/
"It is clear to me that climate change is now becoming such a strong contributor to these hitherto unimaginable events that the language starts to change from one of “climate change increased the chances of an event” to “WITHOUT CLIMATE CHANGE THIS EVENT COULD NOT HAVE OCCURED”."
Again, "we don't know" is not good approach,
best,
Alexander
Posted by: Alexander Ač | February 12, 2009 09:52 AM
Steve, I take your point, it's fair enough.
Bishop, projected changes in rainfall and temperature in Australia can be found in the latest IPCC reports, here for example: http://www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-chapter11.pdf
Alexander, you're absolutely righ in saying that probabilities for extreme weather events, including heatwaves in Europes, have changed already. They will further increase, perhaps double, if temperatures continue to rise. Havin said this, the statement 'WITHOUT CLIMATE CHANGE THIS EVENT COULD NOT HAVE OCCURED' is not true.
The probability of such a prolonged dry spell (I experienced the 2003 heatwave) would have been smaller if average temperatures here had not increased by around one degree - but it would not have been zero.
We have, unfortunately, no means to test what would have happened without climate change. That's in a sense the dilemma: We're conducting an experiment with the planet that we can only do once. The rest, if you will, is statictics. And in climate matters - weather and climate are stochastical phenomenona par excellence - it's pretty important to get the basic statistics right. Please don't confuse my reasoning with denialism. It should be clear to everyone who reads my articles that this would be absurd.
Posted by: Quirin Schiermeier | February 12, 2009 05:04 PM
Dear Quirin,
fair enough, I think. Surely, if I thought Your are in denial, I would not write a comment. I think Climate Feedback is excellent site and I read it regularly,
best,
Alexander
Posted by: Alexander Ač | February 12, 2009 09:11 PM
To find out why more southern drought and more northern rain are expected in Australia, Bishop could read this recent review paper ("Widening of the tropical belt in a changing climate") if he wanted to be informed about the underlying mechanism. Interestingly this same mechanism is needed to make the glacial cycles work ("Ocean circulation in a warming climate"). A possibly related effect has just been discovered ("Changes in the phase of the annual cycle of surface temperature").
So we are changing the basic circulation pattern of the atmosphere, and in the past similar changes have been determined to be key to tipping the planet into completely different climate regimes.
What fun!
Posted by: Steve Bloom | February 12, 2009 10:35 PM
"Firefighters called on the Australian government on Thursday to take a tougher stance against climate change in an effort to avoid more deadly bushfires like those that killed 181 people this week."
Posted by: Steve Bloom | February 13, 2009 02:44 AM
Average temperature trends in Western Australia over the past 100 years ...
http://www.waclimate.net
Posted by: Chris Gillham | April 10, 2009 10:06 AM