What’s the carbon footprint of …a bushfire?

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If you were looking for the single most carbon-intensive thing you could do in your live, starting a bushfire would be a fairly good candidate. That one strike of a match could make your footprint many thousands of times greater than most people achieve over their lifetimes.

The estimate given above is for the catastrophic “Black Saturday” bushfires in Australia last year. It assumes that 450,000 hectares (1750 square miles) of forest containing 100 tonnes of carbon per hectare was burned, and that all of that carbon becomes CO2. It’s an extremely approximate figure, for sure (some of the carbon would doubtless remain in place) but it does give a sense of the scale. To put 165 million tonnes of CO2e into perspective, the most recent estimate of Australia’s entire annual footprint was 529 million tonnes CO2e, so the fires may have added nearly one-third.

Emissions from bushfires vary from year to year. In 1997–98 they are thought to have been around 2.1 billion tonnes. In theory, regrowth will absorb the CO2 from the air in time, thus making the fire carbon neutral in the long term. However, it is looking increasingly likely that permanent changes in terrain are taking place, almost certainly helped along by a nasty feedback loop that sees climate change cause drier forests, which in turn lead to more fires, more emissions and more climate change. And so on.

Furthermore, even if the fires were neutral overall in terms of CO2, they are also a major source of black carbon – also known as soot – which acts as a powerful but short-lived greenhouse gas and one of the key drivers of man-made climate change.

See more carbon footprints.

• This article draws from How Bad Are Bananas? The Carbon Footprint of Everything by Mike Berners-Lee.