Can Los Angeles, devastated by fires, become uninhabitable?

Miles of lives gone up in smoke. On the roads leaving Los Angeles, endless lines of cars carry evacuated residents, resigned to leaving their homes behind to be devoured by fire. Since Tuesday and the start of the first fire, four or five outbreaks have been activated in the north of the city, razing entire neighborhoods, from Pacific Palisades to Malibu. In an area regularly plagued by flames, the return of residents is written in dotted lines.

“Since the Paradise fire in 2018, we have seen an increase in the phenomenon of large fires” in California, confirms Pauline Vilain-Carlotti, doctor in geography and specialist in forest fires. Larger fires, and therefore “increasingly difficult to manage”. In the background, global warming aggravates this dynamic. After a particularly hot year in 2024, “it hasn’t rained since May in Los Angeles”, already affected by fires in September, notes the geographer.

Global warming, a fire accelerator

The violence of the fire is also measured by the damage it causes. In addition to the hundreds of homes engulfed in flames, five people died in Los Angeles. “This lethality is recent,” worries Pauline Vilain-Carlotti, referring to the recent victims of fires in Hawaii and Greece. The geographer points out a “blind spot in fire management”: prevention and adaptation to global warming. “We must take our responsibilities, 90% of fires are of human origin”, whether accidental or criminal.

“Generally speaking, the West of the United States will become drier with climate change,” says climatologist Jean Jouzel. The soils and dry vegetation provide a terrain that is all the more conducive to the spread of flames as the wind has been blowing strongly in recent days. “California is significantly vulnerable to repeated droughts and forest fires,” he says.

In the case of Los Angeles, Pauline Vilain-Carlotti emphasizes “the socio-spatial vulnerability of territories”. In other words, on the urban sprawl of the City of Angels, with large areas “in suburban housing estates with semi-nature” and “a loose road network”. However, these “habitat-forest” structures are the most vulnerable to fires, since they constantly provide fuel for the fire to attack buildings. In addition, the surroundings of the city offer “a very steep territory”, where the fire “strengthens on the ascending slopes of the hills”.

Water, too much or not enough

The 9,000 firefighters mobilized can no longer fight the flames, especially since a precious resource is missing: water. The level of Lake Mead, which supplies part of southern California, remains very low, and fire hydrants quickly found themselves dry. “We find ourselves in a contentious case at the political and media level,” recognizes Pauline Vilain-Carlotti, Donald Trump not holding back from vilifying the management of Democratic Governor Gavin Newsom. “All that remains is to pray that the wind stops or that the rain falls,” Jean Jouzel resolves. But beyond the current fires, “a water war” is brewing, according to Pauline Vilain-Carlotti, who notes “a scarcity of resources in quality and quantity” in this region.

A year ago, the Los Angeles region was underwater, the victim of a storm accompanied by flooding. A vicious circle, explains the geographer. “Alternating extreme precipitation and drought can cause mudslides, and with fires bare soils are more likely to cause landslides. » Turning towards the sea, Jean Jouzel wants to be more measured on another consequence of climate change: “The rise in water levels is more punctual, it is less of a threat for the cities” of California.

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Finally, one last danger awaits California: its geology. The steep hills surrounding Los Angeles are the result of intense seismic activity over millennia. “It’s a very significant risk, which is not climatic,” observes Pauline Vilain-Carlotti. Further north, “the San Andreas Fault is a sword of Damocles above San Francisco,” warns Jean Jouzel. So many elements that make California more and more hostile.