Hydroclimatic fluctuations fuel wildfires in Los Angeles

A research team at the University of California Los Angeles discovered that the wildfires raging in Los Angeles, California, have become intense partly due to the phenomenon of “hydroclimate fluctuations”. New research published in an online journal Nature Reviews Earth and Environment on January 9.

Hydroclimatic fluctuations are sudden, strong fluctuations between extremely wet and extremely dry weather. California experienced record-breaking rain and snow in the winters of 2022 – 2023 and 2023 – 2024. Heavy rainfall promotes plant growth. But by last summer, this vegetation withered under record heat and prolonged drought, becoming flammable dry fuel.

Abundant dry fuel combined with extremely strong Santa Ana winds, a warm, dry northeast wind that blows from southern California to the coast, causing fierce fires in Los Angeles. By January 9, the largest fire, Pacific Palisades, covered an area of ​​more than 70 square kilometers, destroying more than 300 houses. The second largest Eaton fire also burned an area of ​​about 43 square kilometers, destroying many houses and killing at least 5 people.

New research shows that hydroclimatic fluctuations have become 31% – 66% more common globally since the mid-20th century due to climate change. The main reason is the expanding “atmospheric sponge”, as rising temperatures allow the atmosphere to hold and release 7% more water with each degree Celsius of warming.

By the end of the century, such fluctuations could more than double if global temperatures rise by 3 degrees Celsius. Regions around the world, from California to the Middle East and South Asia, are expected to face Wet and dry cycles are getting worse.

“California’s series of hydroclimatic fluctuations doubles the risk of wildfires. First, they cause flammable grass and shrub growth to grow rapidly in the months leading up to fire season, then cause the vegetation to severely dry out with dryness and heat,” said expert Daniel Swain at the University of California Los Angeles, lead author of the new study.

“Hydroclimate variability is likely to increase even more in the future. We really need to take this into account in our risk assessments and adaptation activities,” Swain added.

It is too early to determine the exact cause of the wildfires in Los Angeles. However, given the flammable conditions caused by hydroclimatic fluctuations, the fact that these fires became so intense is not surprising. As California and many other regions around the world face increasing frequency of hydroclimatic fluctuations, proactive planning – preparing for dry periods while we are in the wet period – is essential. – extremely important for minimizing future disasters.