A new study offers a dire prediction for the US state of California, where scientists say catastrophic flooding could double in the future due to the effects of climate change.
Researchers from UCLA and the National Center for Atmospheric Research have completed and published the results of the first part of their “ArkStorm” 2.0 study, which looks for possible climate-induced flooding of “biblical” proportion, also known as “the other big “. in reference to a large earthquake expected on the San Andreas fault.
The study, published Aug. 12 in the peer-reviewed journal Progress of sciencefound that historical climate change has already doubled the likelihood of an extreme storm scenario, and the chance of a “megastorm” is expected to increase with each additional degree of global warming this century.
The study projects that turn-of-the-century storms will create 200 to 400 percent more runoff in the Sierra Nevada mountains due to increased precipitation, more of which will fall as rain rather than snow.
“In the future scenario, the storm sequence is greater by almost every count,” said Daniel Swain, a UCLA climatologist and co-author of the paper. said in a press release.
“There is more rain overall, heavier rain per hour and stronger wind.”
While droughts and wildfires tend to get a lot of attention, Swain said Californians may be losing sight of extreme flooding.
“There is a chance of serious wildfires every year in California, but many years go by without any major flood news,” he said. “People forget about that.”
The state has experienced major flooding in the past, but researchers say nothing has reached the scale of the Great Flood of 1862, when floodwaters spread up to 300 miles long and 60 miles wide in the Central Valley of California, at a time when there was no flood management. infrastructure existed.
California’s population has increased significantly since then from around 500,000 to almost 40 million todayresearchers say.
If a similar Great Flood were to happen now, scientists say parts of Sacramento, Stockton, Fresno and Los Angeles would be under water, a disaster to the tune of US$1 trillion in economic loss and larger than any in world history. .
Flooding is already wreaking havoc on West Coast economies, with major flooding in British Columbia causing $450 million in insured losses, according to the Canadian Insurance Bureau.
The study comes nearly a year after record flooding in November 2021 displaced at least 15,000 people in British Columbia.
Before that, the province experienced an unprecedented heat wave during the summer.
Using new high-resolution weather models and existing climate models, the study researchers compared two extreme scenarios: one occurring about once a century under recent historical climates and the other under a climate projected between the years 2081 and 2100.
Scientists say both scenarios would see a long series of storms fueled by atmospheric rivers – long, narrow regions in the atmosphere that carry water vapor – over the course of a month. The BC flood last November has been linked to the presence of atmospheric rivers.
Climate change increases the amount of rain that the atmosphere can hold, a CNN report in the study it says, leading to more water falling as rain, which can cause immediate flooding.
Referring to the future scenario, Swain said there are localized places that could receive the equivalent of more than 100 inches of water in a month.
Increased runoff could lead to devastating landslides and debris, especially in mountainous areas burned by wildfires, the researchers say.
Major interstate highways such as I-5 and I-80 would likely close for weeks or months, impacting the global economy and supply chains, the researchers add.
But even if meteorologists and climatologists gave weeks’ advance warning of the floods, scientists say it would still not be possible for the five to 10 million people displaced by the floods to evacuate their homes.
The researchers stress that the study was limited due to a lack of organized resources and funding.
Advanced flood simulations done with the support of federal and state agencies are in the works, the scientists say, adding that they hope to map where flooding could be worst.
With archives from CTV News, The Canadian Press and CNN