Deadly East Coast hurricane, California downpours tied to climate change

As Tropical Storm Ida cripples New York City and flooding takes dozens of lives along the East Coast, California suffers from a two-year drought that has curtailed water supplies and spawned wildfires scorching nearly 1,000 square miles.

One side of the nation gets far too much water, the other side far too little,

The common element is climate change and it would be folly for Californians to yearn — even with flames approaching Lake Tahoe, the jewel of the Sierra — for a portion of the rain falling 3,000 miles away.

“I wouldn’t trade places for a hurricane,” said Sonoma County Board of Supervisors Chair Lynda Hopkins.

“These hurricanes are unpredictable, severe, extremely destructive and hitting the most vulnerable hardest,” she said, noting that entire families perished in basements filling with floodwaters.

“We have lost too many who couldn’t escape the flames, and the East Coast lost folks who couldn’t get away from the water fast enough,” Hopkins said. “It’s heartbreaking.”

As a meteorological fact, neither Atlantic Ocean hurricanes nor Pacific Ocean-spawned cloudbursts — known as atmospheric rivers — can cross the continent.

Hurricanes, the most violent storms on Earth, are driven by clusters of storms called tropical waves blown across the ocean from Africa, said Alan Reppert, senior meteorologist for Accuweather, a private forecasting company.

Atmospheric rivers, massive columns of water vapor that dwarf the flow of the Mississippi River, are driven by the jet stream from as far west as Hawaii, he said. They can’t get past the Rocky Mountains going east.

Hurricane season is from June through November, while atmospheric rivers — and virtually all of California’s precipitation — arrives from late fall to early spring.

Both get a boost from the warming planet.

Climate change enabled Ida to rapidly gain strength from a Category 1 to a Category 4 storm in about 24 hours as it moved over abnormally warm water in the Gulf of Mexico, NPR reported.

The ocean was the temperature of bathwater — about 85 degrees Fahrenheit, a few degrees hotter than average — and the extra heat acted as fuel for the storm. As the Earth heats up, rapidly intensifying major hurricanes such as Ida are more likely to occur, the report said.

“In a warmer climate, extreme atmospheric rivers will become more intense as they become wetter, longer and wider,” according to a study published in the journal Science Advances in 2019.

“There is some indication that this is already happening in association with observed Pacific Ocean warming,” the study said.

Making the connection a trifecta, Cal Fire reported climate change is “considered a key driver” of California’s elongated fire season, with blazes erupting this year in every month but February.

There is, however, no comparison between the damage wrought by hurricanes and atmospheric rivers.

New York City was crippled by Ida and the death toll along the East Cost kept growing Thursday, even as the event was downgraded from hurricane to tropical storm.

Central Park recorded more than three inches of rain in an hour Wednesday night, and the total for the day exceeded seven inches, the fifth highest on record.

“It's dangerous. We're seeing a kind of rainfall — we almost never see this kind of speed with which the rain has come,” New York City Mayor Bill de Blasio said, CNN reported.

The heaviest 24-hour rainfall on record in Sonoma County is 12.41 inches at Cazadero on Feb. 26, 2019, according to the National Weather Service.

The following day saw the Russian River crest at 45.38 feet, about four feet below the record of 49.5 feet in the notorious Valentine’s Day flood of 1986, which swamped Guerneville after six days of heavy rain.

Sonoma County is a bull’s-eye for atmospheric rivers, sustaining more than $5 billion in damage from the megastorms over 40 years, the Science Advances study said. The total made it the hardest hit among 414 counties in 11 western states.

In the same period from 1978 to 2017, the study said damage across the 11 states amounted to $50.8 billion.

Ida matched that number, with damage estimated at $50 billion to $60 billion, The Associated Press reported. The nation’s two most destructive storms are $160 billion in damage from Hurricane Katrina in 2005 and $125 billion by Hurricane Harvey in 2017.

The third worst is Hurricane Sandy, which left more than $70 billion in damage in 2012.

Another distinction between hurricanes and atmospheric rivers is the latter are not always harmful.

Atmospheric rivers, with a Jekyll-and-Hyde capacity for dousing droughts and triggering floods, are at the heart of the North Coast’s increasingly variable climate, exacerbated by climate change, the study said.

The massive columns of water vapor deliver close to half of Sonoma County’s drinking water, said Jay Jasperse, chief engineer at Sonoma Water, the agency that supplies water to 600,000 Sonoma and Marin county residents.

“History has shown when we don’t get many atmospheric rivers we are almost always in drought,” he said in a 2019 interview.

But heavy rain is not the proper antidote to drought and fire, officials said.

A downpour wouldn’t end fire season because the ground is so parched, Hopkins said, and it would also risk erosion, especially over the county’s vast wildfire scars, where ground had been left bare.

Jasperse said he is concerned that watershed areas scorched last year haven’t been tested since last winter was so mild.

Ben Nicholls, a Cal Fire division chief who oversees Sonoma County, agreed that too much rain could be harmful.

“The best setup would be a light, steady rain through the winter,” he said. “A day or two of heavy rain followed by a continued period of dry weather would be a very short term relief.”

You can reach Staff Writer Guy Kovner at 707-521-5457 or guy.kovner@pressdemocrat.com. On Twitter @guykovner.