Climate change worsened fires in Southern California

At the beginning of this year, several major fires in the Los Angeles area raged. So far, these fires have demanded 29 lives and destroyed over 16,000 buildings. An international research group has now found that man -made climate change has contributed to the intensity and probability of these major fires.

Dry winds from the mountains

Forest fires are not unusual in Southern California. They usually occur from July to September when low humidity, high temperatures and low rainfall prevail. However, some of the most destructive fire occurred in autumn and early winter when the Santa-Ana winches. These dry winds flock from the mountains in the interior to the coast.

Although it usually rains more in California from October to December, the rains failed to materialize during this period. The region has not experienced any significant precipitation since May 2024, as is the quick analysis of the World Weather Attribution (WWA) scientist initiative at Imperial College London.

Vulnerability of a region

The 32-member research group used the “Fire Weather Index” (fire-weather index, FWI), which uses meteorological information about temperature and wind speed, for example, to characterize the weather conditions that can influence the size of the forest fires. They also examined the drought conditions in the months in front of the fires and compared them with similar patterns from the past seven decades. Simulations helped to understand the effects of climate change on the extent of the fires.

• The results show that the conditions that determine the “Fire Weather Index” have become more extreme. In today’s climate with global warming of 1.3 degrees Celsius compared to the pre -industrial period, these conditions are 35 percent more likely and 6 percent more intensive. This trend has accelerated in recent decades.
• If the warming reaches 2.6 degrees Celsius, which is expected by 2100, these fire -promoting conditions would be more likely to be 35 percent more likely.
• The precipitation poverty from October to December 2024 had the vegetation dry out, which then acted as a fuel. According to the analysis, the current global warming occurs every 20 years and are therefore 2.4 times more likely than in a pre-industrial climate.
• The dry season in Southern California has extended by climate change by 23 days. This overlaps the time in which dry plant material is available as a fuel, with the Santa-Ana wind season. After two very moist winters in 2022/23 and 2023/24, there was plenty of dried out plant material, since the precipitation of this winter would have promoted the growth of grass and shrubs.

The research group emphasizes that the individual results are affected with uncertainties, but all point in the same direction: climate change has increased the likelihood of the fires.

“Attribution studies are a valuable instrument to evaluate how climate change affects the likelihood or intensity of conditions that promote forest fires,” commented Yoshi Maezumi from the Max Planck Institute for Geoanthropology in Jena. This included, for example, long -lasting drought, extreme heat and low humidity.

“However, individual fire events – such as those in Southern California – cannot be fully attributed to climate change, since ignition sources – often people – and local factors such as topography play a decisive role,” added the researcher. “Nevertheless, there are significant indications that climate change has tightened the ‘fire weather’ worldwide, with longer fire season and more extreme conditions in many regions.”