The alternation between weather conditions that are abundantly wet and periods of extreme drought represents one of the most dangerous combinations, as it can facilitate the development of mega-wildfires, such as those that struck the Los Angeles region in recent weeks. This is explained by a study published in the scientific journal Nature, which introduces the concept of "hydroclimate whiplash".

Anomalous vegetation growth and scorching conditions: an explosive mix

California had indeed experienced a prolonged period without rainfall following two particularly rainy winters: those of 2023 and 2024. And this too, according to the scientists' analysis, is one of the consequences of climate change, which is making extreme weather events increasingly frequent and intense.

"Hydroclimate whiplash" thus refers to the succession of such "extremes". Excessively rainy phases trigger anomalous vegetation growth. In 2024, California's summer — and also the autumn and the currently ongoing winter — proved extremely arid, causing the desiccation of plants, shrubs and trees that had previously grown abundantly. In other words, the volatility of weather conditions generated the perfect "fuel" for dangerous wildfires.

"The risk of wildfires in the region has doubled"

According to Daniel Swain, a climatologist at the University of California and lead author of the study, "this sequence of 'whiplash' events in the region has doubled the risk of wildfires. First by dramatically increasing the amount of flammable vegetation, then by drying it out to extremely high levels, also due to exceptional heat waves. The evidence gathered shows that these phenomena are already being exacerbated by global warming, and as it intensifies, things will only get worse."

Daniel Swain ✓ @Weather_West

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In 2024, Southern California experienced an exceptional episode of wet-to-dry hydroclimate whiplash. Very wet conditions in winters of 2023 and 2024 gave way to a record-dry start to 2025 wet season (with periods of record warmth and evaporative demand in between). #CAwx #CAfire

♥ 165💬 7 9 gen 2025 · Apri su X →

More precisely, the study indicates that cases of "hydroclimate whiplash" have increased globally by up to 66 per cent since the mid-twentieth century. And they have done so "even more than climate models had predicted". Looking ahead, even the most conservative scenarios indicate that with an increase in average global temperature of 3 degrees Celsius above pre-industrial levels, there will be a doubling of "hydroclimate whiplash" events.

The atmosphere behaves "like a sponge"

In the study, the phenomenon is compared to the workings of a sponge: as the atmosphere warms, it absorbs more moisture (just as sponges do), drawing it from soils and plants as well. This can trigger wildfires, but can also create conditions ripe for the atmosphere to "wring itself out", releasing the collected water through torrential rainfall.

It is becoming increasingly clear, in short, that climate change risks triggering an ever-growing number of catastrophes. And it is therefore becoming increasingly clear that we must act with the utmost urgency to avert the worst.