Bushfires starting earlier as the climate changes

The new federal environment minister, Greg Hunt, “looked up what Wikipedia says” and concluded that Australia has always had bushfires in hotter months – but if he looked a bit harder, he might find that we’re getting more of those hot months and earlier.

To be sure, Wikipedia is quite reliable; they even say so themselves. But a government minister can probably find more detailed information, as can anyone else if they dig a bit.

One good, independent site is Romsey Australia, which lists major historical bushfires for each Australian state and territory. If you look at the starting date for all the NSW fires listed (from 1926 to 2006) you see the following:

Plot of starting dates of NSW bushfires from 1926 to 2006, with an average for each decade moving earlier in the year

The spread of bushfires throughout the year definitely appears to be increasing, and there’s a clear trend of them starting earlier. Now, it’s likely that the increased availability of data is a factor here, but I reckon this is at least as good as perfunctory ministerial Wikipedia research.

But is this climate change? After all, we also have the prime minister Tony Abbott claiming that “these fires are certainly not a function of climate change,” and that the United Nations climate chief Christiana Figueres was “talking through her hat” when she linked them.

Well, the Intergovernmental Panel on Climate Change (IPCC), in their 2007 Fourth Assessment Report, Working Group II on Impacts, Adaptation and Vulnerability, said that:

Fire frequency is expected to increase with human-induced climate change, especially where precipitation remains the same or is reduced (Stocks et al., 1998).

So far this year in their Fifth Assessment Report, the IPCC has only released the section on the physical science basis, with discussion of impacts yet to come. But they definitely predict that temperatures will continue to increase, and dry areas in the sub-tropics and mid-latitudes are likely to get drier – both factors that contribute to bushfires.

Now, I tend to agree that you can’t attribute a single event (or events, considering there were over 70 burning at the same time) to climate change, but if you look at the trend you see what the scientists were forecasting all along.


One thought on “Bushfires starting earlier as the climate changes

  1. I love “lost in science”. Again and again it tackles questions that are already in my mind and which make me regret my lack of a scientific education. (eg matters relating to health, bushfires and many aspects of daily life.) Their lively, unpretentious presentation makes listening to this programme smething I really enjoy and value.

    I’m really grateful to the presenters for their hard work and dedication and thanks to all 3CR volunteers for making it possible for me to listen to this and other excellent programmes.

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