Climate change caused by emissions from fossil fuels set records again last year and, scientists warn, is leading to increasingly extreme events: heavy rains, heat waves, and droughts. Although it is too early to know whether California’s devastating fires can be directly attributed to global warming — and studies to determine the cause often take time — it is clear that the climate crisis is exacerbating this type of disaster around the world. Moreover, the situation in California perfectly exemplifies the so-called “hydroclimatic strike” that is increasingly occurring on the planet: sudden changes in weather conditions that favor these wildfires.
“A Copernicus (European Service) report has just been published showing that 2024 was the warmest year since records exist. In general, rising temperatures make the environment warmer and drier, which creates all the appropriate conditions for the severity of fires to worsen. “Climate change is exacerbating extreme events and increasingly deadly fires,” explains Mar Gomez, Director of Meteorology at Eltiempo.es and Doctor of Physical Sciences.
“The region is currently experiencing a strong anticyclone located in the interior of the continental United States and a low pressure off the coast of California,” says meteorologist Francisco Martin León — who worked for 38 years at Aemet and now works at Meteored — “This creates a pressure gradient that causes “The wind descends over the mountains in search of the coast, which represents a sharp rise in temperature and increased acceleration.”
Santa Ana or Diablo winds usually blow on the East Coast from October to February, although they are particularly strong on this occasion. “There are winds of up to 100 kilometers per hour, which are very strong, but there are peaks of up to 160 kilometres, which would be considered tornadoes. In that context, any spark, any barbecue, can be a massive ignition element.
What is less common at this time is extreme heat and lack of rain, as Gomez explains: “Right now, temperatures are unusually high in the state. In addition, it usually rains sometimes starting in October, but this year there has been no rain.” It has been raining since July, and this is an anomaly. There has not been a rainy season. He continues: “When a fire breaks out, the conditions for it to spread quickly are less than 30% humidity, more than 30 degrees, and high-speed winds. About 30 kilometers per hour, “all of which occur in California.”
The Meteorred expert points out that at the beginning of 2024, the North American state witnessed heavy rains due to the natural El Niño phenomenon, which helped the growth of plants and vegetation. “But since July, there has been a severe drought, with little rain, allowing the vegetation to dry out, which has led to the drying out of a large number of plants that are fuel for fires, and exceptional weather conditions that are conducive to the expansion of fires.”
Leon points out that “a meteorological phenomenon cannot be directly attributed to climate change, but attribution studies must be conducted, using numerical models, to find out how frequently a phenomenon like this occurs without climate change.” But in any case, “everything seems to indicate that anthropogenic climate change is behind us, as it encourages longer periods of drought, more global warming, and more intense low- and high-pressure systems.”
Gomez agrees: “We know that fires will become increasingly more powerful and more damaging, and this is within the predictions that climate scientists have been warning about for years.”
The concept now being linked to the California fires is “hydro-climate strike.” It refers to the rapid changes between an extremely humid climate and a dangerously dry climate, a phenomenon that is increasing around the world, according to an article published this week in the journal Nature Reviews. The example of California is used to illustrate the point: Last winter was very wet in southern parts of the state, but then summer brought record heat and the onset of drought. The result is a lot of vegetation, which then dries up and becomes fuel for wildfires.
“Hydro-climate strikes have already increased due to global warming, and further warming will lead to even greater increases,” said Daniel Swain, a climate scientist at the University of California (UCLA) and lead author of the study, which concluded that this hydro-climatic phenomenon has increased. Globally between 31% and 66% since the mid-twentieth century. “This cascade of infestations in California has exponentially increased fire danger: first, by greatly increasing the growth of flammable grass and brush in the months leading up to fire season, and then by drying it out to exceptionally high levels with drought.” The intense heat that followed.
Although in California’s case we’ll have to wait and see what the attribution studies say, according to the researchers, human-induced climate change is causing more evaporation and water into the atmosphere, releasing 7% more water for every degree Celsius rise. global warming, and this is closely linked to hydroclimatic injury.
