Drought and forest fires are the headline disasters this season. But California also faces the threat of another kind of calamity, one that could affect the entire state and cause more economic damage than a big earthquake on the San Andreas Fault.
Posted at 6:00 a.m.
New research from climate scientists has found that the risk of a month-long superstorm, which would shower northern and southern California with staggering amounts of rain and snow, is increasing rapidly due to global warming caused by the man. According to the study, each year, the probability of such a storm occurring is already about 1 in 50. And this probability continues to increase as we release greenhouse gases into the atmosphere.
Warmer air holds more moisture, which means atmospheric rivers — those storms that come in from the Pacific and are sometimes called the “Pineapple Express” — can carry greater amounts of precipitation.
California has been hit by giant atmospheric river-fed storms before. A particularly devastating storm, which occurred in 1861-1862, turned the Central Valley into an inland sea.
Sacramento had been so badly flooded that Governor Leland Stanford had to row a boat to his inauguration ceremony in January 1862, according to the Sacramento History Museum. The state legislature had also moved temporarily to San Francisco.
The state has since dammed its rivers and built bypasses to direct floodwaters away from population centers. If this storm of the XIXe century struck today, all this infrastructure would reduce the risk of destruction. However, the state is also much more developed – with larger cities, higher value farms and businesses, and a much larger population – which means the consequences could still be significant.
INFOGRAPHIC LA PRESSE, SOURCE THE NEW YORK TIMES
The good, and the not so good, side of the preparations
If there’s any good news in all of this, it’s that many planners and decision-makers are aware of the risks. The Department of Water Resources plans to use new scientific findings to update state flood plans. With the help of supercomputers, he will establish a detailed map of the flow of all this precipitation in the waterways and on the land.
California is also working to strengthen levees in urban areas of the Sacramento and San Joaquin valleys to provide protection against storms that occur every 200 years, i.e. those with 0.5% of chances of occurring in a given year.
There’s a flip side, however, that the risk of flooding has become something many Californians never think about because of all these preparations.
From one point of view, this is progress: most of us have better things to do every day than worry about nature’s wrath. But there are also dangers in not thinking that you live in a danger zone. You can ignore evacuation orders, downplay storm forecasts, deny flood insurance.
“When the government takes care of these dikes, most homeowners are hopeful that we are doing the right thing and that they can put their savings in a safe house,” said Ricardo Pineda, a retired engineer. of the state as we recently toured the Sacramento flood management works.
“They like to walk their dogs on the seawall,” he added. [Mais] are they prepared for the economic consequences of a flood like the one in New Orleans? »
In Lathrop, near Stockton, the planned community River Islands sits in an area of the San Joaquin River that was horribly flooded in a storm in 1997. The developer built extra-wide levees, without using public funds, to protect the charming houses and tidy streets.
Susan Dell’Osso, president of River Islands Development, points out that many of her buyers were from the Bay Area and asked pointed questions about schools and life in the Central Valley.
“They never ask about the floods,” Ms.me Dell’Osso. She tries to educate them about it, she says. But “they don’t even realize, I think, there is a risk”.
This article was first published in the New York Times