In recent times there has been much discussion about whether or not climate change contributes to the massive forest fires in Australia. The most exact answer that science can give was published on Wednesday. The short answer is: yes, at least 30 percent.
That is a lower limit, say specialized researchers. The role of climate change can be considerably larger, but not smaller. In addition, the weather always remains a factor. Part of the causes of the extreme drought that hit Australia last year is therefore natural.
This is apparent from a comprehensive scientific study into the causes of the forest fires. The research was conducted by World Weather Attribution, a scientific network of specialized climate scientists. A total of eighteen researchers from various institutes participated in the study.
Geert Jan van Oldenborgh from KNMI is the lead author of the study. He tells NU.nl that climate change has increased the chance of weather conditions causing persistent forest fires.
“That increase is at least 30 percent, but it can also be much more. That’s because climate models underestimate the real trend for extreme heat. The models therefore all give too low a value for the increase in the chance of such weather.”
“People forget to take the influence of heat with them”
The risk of forest fires in particular has increased due to heat. The precipitation in Australia, on the other hand, remains fairly constant with alternating wet and dry years. Van Oldenborgh: “There are people who sometimes forget to take the influence of heat on the risk of forest fires with them. A higher temperature dehydrates the fuel in the forest further, so that it can burn faster and more intensively.”
“Another problem is that the word drought has so many meanings. You can see it as simply low rainfall. But a more relevant meaning is soil drought: the moisture deficit in the soil. That depends not only on precipitation, but also on evaporation. Evaporation increases due to higher temperatures. Along that route, climate change increases the risk of forest fires. “
The chance of forest fires increases further as the earth warms up further
Attribution research is a relatively new branch in climate science, where the influence of climate change on an event with extreme weather can be calculated retroactively. This is done by having a large number of climate models run in two positions: one with the original climate and one with the current, heated climate. If the warming trend leads to an increase in the chance of an extreme deviation, it can be calculated precisely in this way.
Not all weather extremes are reinforced by climate change, says Van Oldenborgh. But the connection with the Australian drought is clearly demonstrable. It can also be deduced from the study that the likelihood of similar extreme forest fires increases if global warming continues.
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