California's past megafloods – and the coming ARkStorm

Guest Essay By Larry Kummer. Posted at the Fabius Maximus website.

Summary: To boost our fear, activists and journalists report the weather with amnesia about the past. Ten year records become astonishing events; weather catastrophes of 50 or 100 years ago are forgotten. It makes for good clickbait but cripples our ability to prepare for the inevitable. California’s history of floods and droughts gives a fine example — if we listen to the US Geological Survey’s reminder of past megafloods, and their warning of the coming ARkStorm.

” A 43-day storm that began in December 1861 put central and southern California underwater for up to six months, and it could happen again.”

— “California Megaflood: Lessons from a Forgotten Catastrophe” by B. Lynn Ingram (prof of Earth Science, Berkeley) in Scientific America, January 2013.

Lithograph of K Street in Sacramento, CA during the 1862 flood. From Wikimedia commons.

One of the key events in California history has disappeared from our minds. For a reminder see this by the US Geological Survey.

“Beginning on Christmas Eve, 1861, and continuing into early 1862, an extreme series of storms lasting 45 days struck California. The storms caused severe flooding, turning the Sacramento Valley into an inland sea, forcing the State Capital to be moved from Sacramento to San Francisco for a time, and requiring Governor Leland Stanford to take a rowboat to his inauguration. William Brewer, author of Up and Down California in 1860-1864, wrote on January 19, 1862, ‘The great central valley of the state is under water — the Sacramento and San Joaquin valleys — a region 250 to 300 miles long and an average of at least twenty miles wide, or probably three to three and a half millions of acres!’

‘In southern California lakes were formed in the Mojave Desert and the Los Angeles Basin. The Santa Ana River tripled its highest-ever estimated discharge, cutting arroyos into the southern California landscape and obliterating the ironically named Agua Mansa (Smooth Water), then the largest community between New Mexico and Los Angeles. The storms wiped out nearly a third of the taxable land in California, leaving the State bankrupt.

“The 1861-62 series of storms were probably the largest and longest California storms on record. However, geological evidence suggests that earlier, prehistoric floods were likely even bigger. There is no scientific evidence to suggest that such extreme storms could not happen again. However, despite the historical and prehistorical evidence for extreme winter storms on the West Coast, the potential for these extreme events has not attracted public concern, as have hurricanes. The storms of 1861-62 happened long before living memory, and the hazards associated with such extreme winter storms have not tested modern infrastructure nor the preparedness of the emergency management community.”

For an account of the flood from that time see this by J. M. Guinn; an excerpt from Exceptional Years: A History of California Floods and Drought (1890). Red emphasis added.

Flooded area in California: 1861-1862. From The West without Water.

“The great flood of 1861-62 was the Noachain deluge of California floods. During the months of December, 1861, and January, according to a record kept at San Francisco, 35 inches of rain fell, the fall for the season footed up nearly 50 inches {average is 24 inches/year}. As in Noah’s the windows of heaven were opened, and the waters prevailed exceedingly on the face of the earth.

“The valley of the Sacramento vast inland sea; the city of Sacramento was submerged and almost ruined. Relief boats on their errands of mercy, leaving the channels of the rivers, sailed over inundated ranches, past floating houses, wrecks of barns, through vast flotsams, made up of farm products farming implements, and the carcasses of horses, sheep and cattle, drifting out to sea.

“…To the affrighted vaqueros, who had sought safety on the hills, it did seem as if the fountains of the great deep really been broken up, and that the freshet had filled the Pacific to overflowing. The Arroyo Seco, swollen to a mighty river, brought down from the mountains and canons great rafts of drift-wood …{that} furnished fuel to poor people of the city for several years.

“It began raining on December 24, 1861, and continued for thirty days, with but two slight interruptions. The Star published the following local: ‘A Phenomenon – Tuesday last the sun made its appearance. The phenomenon lasted several minutes and was witnessed by a great number of persons.’

“…After the deluge, what? The drought. It began in the fall of 1862, and lasted to the winter of 1864-65. The rainfall for the season of 1862-63 did not exceed four inches, and In the fall of 1863 a few showers fell, but not enough to start the grass. No more fell until March. The cattle were of gaunt, skeleton-like forms, moved slowly of food. Here and there, singly or in small weak to move on, stood motionless with of starvation. It was a pitiful sight. …

“The loss of cattle was fearful. The plains were strewn with their carcasses. In marshy places …the ground was covered with their skeletons, and the traveler for years afterward was often startled by coming suddenly on a veritable Golgotha — a place of skulls — the long horns standing out in defiant attitude, as if protecting the fleshless bones. …The great drought of 1863-64 put an end to cattle raising as the distinctive industry of Southern California.”

For a more detailed account see “California Megaflood: Lessons from a Forgotten Catastrophe” by B. Lynn Ingram (prof of Earth Science, Berkeley) in Scientific America, January 2013 (PDF here).  The risk of such megafloods remains today as shown in the video “Central Valley Flood Risk” by the California Department of Water Resources and the Corps of Engineers, July 2011.

Why is flood risk so high in California? This video explores the history, risk and government efforts to reduce flooding with one of the world’s largest flood risk reduction systems.

It will happen again: the ARkStorm Scenario

The ARkStorm scenario was prepared by the US Geological Survey, who gathered a team of 117 scientists and engineers — with contributions from 42 Federal, California, and local agencies and universities. Here is the opening of the introduction to the ARkStorm Scenario. For more information see the press release and the full report.

“The ARkStorm storm is patterned after the 1861-62 historical events but uses modern modeling methods and data from large storms in 1969 and 1986. The ARkStorm draws heat and moisture from the tropical Pacific, forming a series of Atmospheric Rivers (ARs) that approach the ferocity of hurricanes and then slam into the U.S. West Coast over several weeks. Atmospheric Rivers are relatively narrow regions in the atmosphere that are responsible for most of the horizontal transport of water vapor outside of the tropics.

“Using sophisticated weather models and expert analysis, precipitation, snow lines, wind, and pressure data, the modelers characterize the resulting floods, landslides, and coastal erosion and inundation that translate into infrastructural, environmental, agricultural, social, and economic impacts. Consideration was given to catastrophic disruptions to water supplies resulting from impacts on groundwater pumping, seawater intrusion, water supply degradation, and land subsidence.

“…Megastorms are California’s other Big One. A severe California winter storm could realistically flood thousands of square miles of urban and agricultural land, result in thousands of landslides, disrupt lifelines throughout the state for days or weeks, and cost on the order of $725 billion. This figure is more than three times that estimated for the ShakeOut scenario earthquake, that has roughly the same annual occurrence probability as an ARkStorm-like event.”

Conclusions

“We don’t even plan for the past.”

— Steven Mosher (member of Berkeley Earth; bio here), a comment posted at Climate Etc.

The political gridlock on public policy relating to climate change has prevent the most obvious and easy first step — preparing for the almost inevitable repeat of past extreme weather. Events like superstorm Sandy and Hurricane Katrina were warnings, showing our mad lack of preparation for likely weather events. Unless we change soon, we will pay dearly for our folly.

For More Information

This is a follow-up to Lessons learned from the end of California’s “permanent drought”. For more about the great flood see Wikipedia and a brief but eloquent account in the 21 January 1862 New York Times.

For more information about this vital issue see The keys to understanding climate change, and especially these …

1. Ten years after Katrina: let’s learn from those predictions of more & bigger hurricanes.
2. An eminent climate scientist explains what caused the record rains in Texas.
3. Have we prepared for normal climate change and non-extreme weather?
4. Let’s prepare for past climate instead of bickering about predictions of climate change.
5. Droughts are coming. Are we ready for the past to repeat?
6. The bottom line: How we broke the climate change debates. Lessons learned for the future.
7. Important: Climate scientists can restart the climate change debate – & win.