Visual explanation: why are the wildfires in LA so bad? | American wildfires

EIn a state that has grown grimly accustomed to severe fires, the rapid spate of wildfires that have ignited the Los Angeles area has been shocking, sparking mass evacuations that have left charred suburban homes.

About 50,000 people have been ordered to evacuate amid three large, fast-moving fires that have consumed thousands of acres near the heart of America’s second-largest city, with one raging in the western Pacific Palisades and the other in the eastern mountains above. Pasadena. An additional, smaller fire is burning in the northern Los Angeles suburb of Sylmar.

The fires have caused at least two deaths and several significant injuries. Gavin Newsom, California’s governor, called the situation “unprecedented” as he ordered 1,400 firefighters to help put out the flames. The fires turned the sky a dystopian orange, knocked out power to hundreds of thousands of people, sparked panicked flights that caused cars to pile up on roads, and burned dozens of homes, including those of Hollywood movie stars in Malibu.

A video of structures and hillsides engulfed in burning flames

Although fire is not new to California, several factors have helped fan the flames, leading to “one of the most significant wildfires in history,” according to Ariel Cohen, a meteorologist with the National Weather Service in Los Angeles, who warned of an impending “disaster”. He added: “I’m imploring everyone – if you receive that evacuation order, take it seriously. Your life depends on it.”

So why have the fires been so bad?

Three major fires in LA Counties: Palisades, Hurst and Eaton

Map of Los Angeles with burned area, evacuation orders and evacuation warnings for each.

Map of the Palisades Fire indicating burned area

Strong Santa Ana winds can ignite sparks

The fires have been spread at a rapid pace by fierce winds that have hit 80 mph (129 km/h), even reaching 100 mph (161 km/h) in some mountainous areas.

California’s cooler months often bring what are known as Santa Ana winds, which are the strong, dry gusts that blow into Southern California from the vast western desert interior of the United States.

These winds bring dry, warm air that pushes toward the coast, the opposite of the usual moist air that blows in from the Pacific Ocean to the region.

This causes humidity to drop, helping to dry out fire-prone vegetation and fueling flames. The Santa Ana winds have contributed to some of California’s worst fires in the past.

“This is an especially dangerous situation — in other words, this is about as bad as it gets in terms of fire weather,” the National Weather Service warned ahead of the latest blazes in Los Angeles.

Map of California and Nevada showing estimated sustained wind speeds

Dry conditions follow the wet

Along with the strong winds, recent conditions in Southern California have added literal fuel to the fire. Two winters of heavy rainfall, notably in 2022 and 2023, caused vegetation to sprout across the Los Angeles region, but this winter has been unusually dry, with much of Southern California locked in drought.

This means that there are plenty of trees, grasses and bushes that can ignite, and most of them are dried out of water, which means they burn more easily.

While Northern California has received plenty of rain this winter, there is a “remarkable” distribution of precipitation in the state, according to to climate scientist Daniel Swain, with parts of Southern California experiencing their driest periods in more than 150 years.

“It’s really a matter of rainfall ‘haves’ and ‘have nots’ at the moment and there’s no real prospect of this changing in the near term,” Swain said. “Even in the long term, it is still possible that this overall dipole will continue for the rest of the season, though hopefully with less extreme intensity.”

Map of California showing drought conditions

The climate crisis brings the heat

While the collision of strong winds and dry conditions has exacerbated the fires burning Los Angeles, the impact of the climate crisis is making such flames more common and destructive.

Until just two years ago, California was in the throes of a decades-long drought that was part of a broader “mega-drought” across the United States that scientists estimate was the worst in at least 1,200 years. Rising global temperatures, caused by the burning of fossil fuels, have caused an increase in “fire weather” days due to drying of vegetation and soil and lowered humidity.

Fires in the western United States are becoming more frequent and larger, researchers say have foundwith climate change increasing the risk of fast-moving fires with about 25% in California. Ten of the largest wildfires in California have occurred in the past two decades, with five of those fires occurring in 2020 alone.

Researchers have calculated that the anthropogenic climate emergency has contributed to a 172% increase in California’s burned areas since the 1970s, with further spread expected in the coming decades.