The effects of climate change are being felt strongly in California in the form of wildfires. However, it is not the only consequence of global warming that threatens the most populous state in the United States.
A study from the University of California at Los Angeles (UCLA) on Friday shows that global warming has doubled the risk of a mega-flood, which can be as devastating as the Great Flood of 1862.
“In the future scenario, the sequence of storms is greater in almost all respects,” said Daniel Swain, a climate scientist and co-author of the paper, published Friday in the journal Science Advance. “There is more rain overall, heavier rain per hour and stronger wind.”
If a storm similar to the one of 160 years ago occurs in California, more than 10 million people would be displaced, major highways such as Interstates 6 and 80 would be closed for months, and the population of urban centers such as Stockton, Fresno and parts of Los Angeles would be submerged.
All this would cause millionaire losses of over a billion dollars, which would make this flood the most expensive natural disaster in history.
The research projects that turn-of-the-century storms will generate 200% to 400% more erosion in the Sierra Nevada due to increased precipitation and more rain instead of snowfall.
In total, the research projects that turn-of-the-century storms will generate 200% to 400% more runoff in the Sierra Nevada mountains due to increased precipitation and more precipitation as rain, not snow.
Our initial atmospheric modeling results presented here demonstrate that extremely severe winter storm sequences, previously considered exceptionally rare events, are likely to become much more common under essentially all possible future climate tracks. .
The researchers used a combination of new high-resolution weather models and existing climate models to compare two extreme scenarios: one that would occur about once a century in the recent historical climate, and one in the projected climate of 2081-2100.
Both would involve a long series of storms fed by atmospheric rivers over the course of a month. The document also simulated how the storms would affect parts of California locally.
“There are localized places that get more than 100 inches (250 centimeters) of liquid-equivalent water in the month,” Swain said, referring to the future scenario.
Increased erosion could lead to devastating landslides and debris flows, particularly in mountainous areas burned by wildfires.
The paper, co-authored by climate scientist Xingying Huang, found that historical climate change has already doubled the likelihood of such an extreme storm scenario, building on previous UCLA research showing increases in extreme precipitation events and major flooding. most common in California.
The study also found that “megastorm” risks are likely to rise further with each additional degree of global warming this century.