The politicised Tathra bushfires explained

By THOMAS KELSALL

Earlier this month, a bushfire swept through the small coastal city of Tathra, NSW, destroying 65 homes, 35 caravans, and small cabins. 

According to the Rural Fire Service, faulty power lines and electrical infrastructure is most likely to blame for the disaster.

Although this was a relatively small bushfire, the political fallout has been disproportionately large.

Speaking to the Senate on March 19, Greens leader Richard Di Natale blamed climate change for the increased risk of bushfires, and strongly criticised the Turnbull government for its current energy plan.

“In our everyday lives we are seeing climate change have an impact on the risk of bushfires to our communities, and we can’t any longer be complacent about bushfires once the end of summer comes around,” Mr Di Natale said.

“Right now we would normally be talking about the end of the bushfire season, and yet here we are with bushfires ravaging my home state.

“In spite of this overwhelming evidence of the impact of climate change, what we’re seeing is a Turnbull government dangerously wedded to coal. It’s pushing against the tide of clean energy and all the benefits that brings.”

Prime Minister Malcolm Turnbull, speaking in Tathra, expressed his disappointment at the Greens for ‘politicising’ the disaster.

“I’m disappointed that the Greens would try to politicise an event like this. You can’t attribute any particular event, whether it’s a flood or fire or a drought or a storm – to climate change,” Mr Turnbull said.

“We have an environment which has extremes. Bushfires are part of Australia, as indeed are droughts and floods. Nature hurls her worst at Australians, always has, and always will.”

But how can we accurately quantify the impact of climate change on Australia’s bushfires?

Bushfires are in fact, incredibly complex, and to isolate the influence of climate change is a difficult task.

A 2015 report by the NSW Office of Environment and Heritage (OEH) illustrates this point.

Rather than coming to a definitive conclusion, the report highlights how climate change has varying effects on each of the four criteria required to start a bushfire.

The first of the criteria is the fuel load or the amount of vegetation that can be burnt in an area.

This, along with the second of the criteria, fuel dryness, often go hand in hand when bushfires occur due to the amount of dry vegetation that can catch fire.

Increased carbon dioxide (C02) in the atmosphere can contribute to drying out a lot of the vegetation but may also improve the water efficiency of plants, countering these negative effects.

One of the problems the OEH report points out is the difficulty in measuring fuel changes.

There is no long-term research on fuel growth in Australia, and it is also unclear whether vegetation growth is more dependent on C02 or nutrients.

Fire weather is the third criteria required for a bushfire, and the impact of global warming is much clearer here.

According to the OEH report, between 1973 and 2010, 16 of 38 Australian fire stations reported an increase in fire conducive weather conditions and none of them recorded a decrease.

A 2011 report by the Department of Climate Change and Energy Efficiency found the catastrophic bushfires in South-Eastern Australia were in large part due to abnormally low rainfall and record-high temperatures.

The report links these two weather occurrences to the Indian Ocean Dipole (IOD), a recent phenomenon where significant differences form between the temperature of the East and West Indian Ocean.

In a positive IOD year (where the West is cooler than the East), substantially fewer clouds form over Australia due to the cooler water temperatures and downward winds.

The Department’s report says Australia’s worst bushfire events have usually occurred after positive IOD events, including the Ash Wednesday, Black Saturday and Canberra bushfires.

The last of the criteria for a bushfire is an ignition source.

A 2006 report from the Bushfire Cooperative Research Council says climate change will cause a large increase in lightning strikes, the most common natural ignition source of bushfires.

But climate change is not the core problem of ignition, as direct human activity starts most bushfires.

Therefore, the influence of climate change on purposely-lit fires will be limited significantly.

There is a scientific consensus that climate change will lead to more extreme weather events, but the issue of bushfires is not as straightforward.

Assertions that climate change is the primary cause of bushfires avoid some important points of scientific nuance.

However, suggestions that Australian weather has always been this harsh prevents us from achieving meaningful action on global warming.

 

 

Image Source: Chris Bowles/The Guardian

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