Daniel Swain, a UCLA climate scientist and co-author of the ARKStorm 2.0 report, said that severe ones like the recent storms, bombarding California with half a year’s worth of rainfall in three weeks, could potentially account for less than half the rainfall with ARKStorm. Published last year.
The biblical-sounding name stands for Atmospheric River 1000. Such a megastorm would likely exceed the Great Flood of 1862, which inundated an area 300 miles (480 km) long and 20 miles (32 km) wide in California’s Central Valley. The valley lies west of the north-south Sierra Nevada mountain range and includes the smaller San Joaquin Valley.
Swain said that an event like 1862 could cause losses of $1 trillion. Swain said the worst-case scenario is about 1% likely to occur next year and that the chances increase in subsequent years “because our climate is making it more likely over time.”
There is also a reduced ARKStorm scenario that would still be one-fourth to one-third more than recent rainfall.
“I don’t know when the decade for extreme flooding is going to come. It could be this decade. It may not be until 2050, although I would put my money on it being closer to this decade than 2050,” Swain said. Said .
Swain, who is unaffiliated with River Partners, said he was “appalled” to see flood protection cuts in Governor Gavin Newsom’s 2023-24 budget proposal published in January, coincidentally in the midst of extreme flooding.