New Study Warns of Weather Disaster ‘Larger Than Any in World History’ in California

by Lauren Boisvert

The western United States is dealing with weather disasters in the form of monster drought and heatwaves right now, but there’s more extreme weather that could threaten California in particular. Megafloods could be on the horizon for the state, according to a new study. Because of climate change, heavy rainfall and subsequently intense flooding are more likely. We’re talking floods that could submerge cities, causing millions of people to lose their homes.

The study posits that a month-long storm over California could cause up to 8 feet of rain in some areas. According to Daniel Swain, co-author of the study and climate scientist at UCLA, weather disasters hitting a warmer planet means “the storm sequence is bigger in almost every respect. There’s more rain overall, more intense rainfall on an hourly basis and stronger wind.”

The study made it clear that climate change is a direct influence on the amount of flooding that could occur in the future. According to Swain, we’ve drastically underestimated the risk of megafloods. In 1862, there was the Great Flood in California, which was 300 miles long and 60 miles across. It was caused by a warm storm that melted heavy snows in the mountains as well as record amounts of rainfall and snow for 43 days. Additionally, the floods were preceded by a 20-year drought. The heavy rains were caused by atmospheric rivers, which are bands of water vapor that originate in the tropics that can produce intense amounts of rainfall. And that was all before climate change altered the state and temperature of Earth.

Why Megafloods and Climate Change Should Be Taken Seriously

The 1862 flood killed 4,000 people, roughly 1% of California’s population. 1% of the population in California now is about 391,856 people. There’s the possibility that a megaflood now could displace 5 million to 10 million people. Parts of Los Angeles could be submerged, with major freeways destroyed or cut off. With such a densely populated state, the economic devastation and loss of human life would be astronomical.

The 1862 flood cost $100 million. Today, a flood of those proportions would cost $1 trillion. And UCLA is predicting a weather disaster possibly worse than 1862. “Parts of cities such as Sacramento, Stockton, Fresno and Los Angeles would be under water even with today’s extensive collection of reservoirs, levees and bypasses,” said UCLA climate scientists in a statement. “It is estimated that it would be a $1 trillion disaster, larger than any in world history.”

According to Swain, wildfires and droughts get most of the attention because they happen most often. People tend to forget about the risk of flooding until it happens, like the recent floods in Kentucky. “There is potential for bad wildfires every year in California,” said Swain, “but a lot of years go by when there’s no major flood news. People forget about it.”