As atmospheric science professor Andrew Gressler of Texas A&M University points out, the fires that hit the Los Angeles area this month required a sequence of three events:
- a period of unusual precipitation (this was the case in winter 2024), which accelerates the growth of vegetation;
- followed by a period of prolonged drought and high temperatures (this has been the case since summer 2024), which turns this more abundant vegetation into a time bomb; a little thing can then start a fire;
- if we add strong winds, as is the case this month, this fire quickly becomes out of control.
Droughts were therefore not “invented” by global warming. But this “overloads” or “overfeeds” them. Likewise, Gressler compares, that warming “overloads heatwaves and hurricanes.”
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An American study just published on January 9 concludes that global warming has increased by 31 to 66%, since the middle of the 20th century, the variability of weather conditions, which increases the risk of situations like those described above: periods more intense rains followed by periods of more intense droughts.
In the specific case of California, other factors come into play, such as urban growth in these “at risk” territories, which considerably increases the probability that, sooner or later, an incident will trigger a fire. Or like the management of forests over the past century which, by leaving more organic material in the forests and undergrowth, provides more fuel.
-It is these “other” factors that climate skeptics systematically seize to claim that global warming is not to blame – forgetting that in the Canadian North or in Alaska, recent years have also seen an increase in forest fires, where there is no urban growth.
As a result, Gressler reminds us, “the real scientific question is not whether climate change had an influence on the fires. They obviously had one. The real question is rather to quantify this impact: by how much does climate change increase the intensity or probability of this or that specific event? This is the question that thousands of scientists have been working on for years—whether quantifying the increased risks of fires, floods, or hurricanes.
For those who still choose denial, there is in any case an economic incentive to want to predict the impacts: as of January 12, the meteorological firm AccuWeather estimated the damages in California between $135 and $150 billion. And it’s not over yet.
