Preface. Hurricane Katrina cost somewhere between $109 and $250 billion dollars (Amadero 2017). Estimates of hurricane Harvey range from $100 to $190 billion (Kollewe 2017, Lanktree 2017).
The next California ArkStorm is likely to cost $900 billion, or even a trillion dollars (NRA 2013 Schlosberg 2020).
The USGS has studied how often a mega storm like the one in 1861-1862 might often, and calculated about every 100 to 200 years (SD 2011, Sullivan 2011). Or perhaps more often: A UCLA study found that over the next 40 years, the state will be 300 to 400% more likely to have a prolonged storm sequence as severe as the one that caused the last Arkstorm in 1861-1862 (Swain 2018).
The 1861-62 series of storms were the largest and longest California storms in the historic record, but were probably not the worst California has experienced. Geological evidence indicates that floods that occurred before Europeans arrived were bigger.
Scientists have found that California Arkstorm mega floods occurred at some time in each of these time frames (dating isn’t precise enough to pinpoint the exact year): 1235–1360, 1295–1410, 1555–1615, 1750–70 and 1810–20, or one mega- flood every 100 to 200 years (Dettinger 2013).
This will affect everyone in the United States since California provides one-third of America’s food, and the flood will cover the prime level farmland of the central valley where nearly all the food is grown. If major dams are destroyed, that will affect future crops because dam irrigation allows 2 to 3 crops a year in California’s benign climate.
Climate change makes the odds of another Arkstorm even greater. Today the west coast gets rain or snow from atmospheric rivers 25 to 40 days a year, by 2100 this may rise to between 35 and 55 days a year (Upton 2016). The storm is estimated to produce precipitation that in many places exceeds levels only experienced on average once every 500 to 1,000 years. The event would be similar to exceptionally intense California storms which occurred 156 years ago between December 1861 and January 1862
In the news:
ARKSTORM 2 Huang X, Swain DL (2022) Climate change is increasing the risk of a California megaflood. Science DOI: 10.1126/sciadv.abq0995 Abstract: Here, we investigate the physical characteristics of “plausible worst case scenario” extreme storm sequences capable of giving rise to “megaflood” conditions. We find that climate change has already doubled the likelihood of an event capable of producing catastrophic flooding, but larger future increases are likely due to continued warming. We further find that runoff in the future extreme storm scenario is 200 to 400% greater than historical values in the Sierra Nevada because of increased precipitation rates and decreased snow fraction.
Future extreme storm sequences will bring more intense moisture transport and more overall precipitation, along with higher freezing levels and decreased snow-to-rain ratios that together yield runoff that is much higher than that during historical events. In addition, we find even larger increases in hourly rainfall rates during individual storm events, which have high potential to increase the severity of geophysical hazards such as flash flooding and debris flows. This is especially true in the vicinity of large or high-intensity wildfire burn areas, which are themselves increasing due to climate change (39) and yielding large increases in associated compound hazards (43).
Zhong R (2022) The coming California megastorm. New York Times.
Alice Friedemann www.energyskeptic.com Author of Life After Fossil Fuels: A Reality Check on Alternative Energy; When Trucks Stop Running: Energy and the Future of Transportation”, Barriers to Making Algal Biofuels, & “Crunch! Whole Grain Artisan Chips and Crackers”. Women in ecology Podcasts: WGBH, Jore, Planet: Critical, Crazy Town, Collapse Chronicles, Derrick Jensen, Practical Prepping, Kunstler 253 &278, Peak Prosperity, Index of best energyskeptic posts
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USGS. 2011. Overview of the ARkStrom Scenario. Open file report 2010-1312. 201 pages. United States Geological Survey and US Dept of the Interior.
Atmospheric Rivers: an Amazon river in the Air
Atmospheric rivers occur around the world and can dump as much rainfall as hurricanes, carrying as much water as the Amazon river (Mackenzie). At any given moment there are about half a dozen atmospheric rivers above the earth. many drop their rain over the ocean before reaching land.
Most aren’t harmful — California gets up to half its precipitation this way. The problem comes when other weather systems cause these airborne rivers to stall out.
Climate change means that the air warms it will hold even more moisture, and atmospheric rivers even wetter, likely to form more often, last longer, and lead to more devastating floods in California (Dettinger 2011).
ARkStorm: A $725 Billion Flood in California is expected
Super Storms occur every 100 to 200 years in California. The most recent super storm was in 1861-62 and lasted 45 days. Massive floods resulted. The Sacramento Valley became an inland sea.
These storms cause far more damage than earthquakes. The State of California estimates the next storm could cost $725 Billion dollars (NRA).
The effects would ripple out to the rest of the United States: California produces nearly half of U.S.-grown fruits, nuts, and vegetables; and across the nation, U.S. consumers regularly purchase several crops produced solely in California.
The USGS (2011) has dubbed such a storm an “ARkStorm” and held a conference to present the findings of more 117 scientists, engineers, and other experts of how such a storm would affect California. A super storm might produce 10 feet of rain, overwhelming flood-protection systems, and perhaps the Oroville dam (Cahill 2017), the United States tallest dam (Wikipedia). Climate change will increase both the likelihood and severity of these storms.
Here are the likely effects of such a storm
- 25% of all homes damaged in California from flooding and landslides
- $300 billion property damage mostly from flooding
- $400 billion damage to Agriculture and landslide damage
- $325 billion in business interruption costs
- A grand total of about $1 Trillion damage of which $20-30 billion would be recovered through insurance (public and commercial)
- Most costly disaster in USA history
- Hurricane force winds up to 125 miles per hour
- Thousands of square miles of agricultural and urban land flooded up to depths of 20 feet.
- Central Valley flood likely to be 300 miles long and 20 or more miles wide
- Hundreds of landslides would cover roads, highways, and homes
- Power outages, water and sewer infrastructure could take months to repair
- Unemployment rate would increase by 6%
- The levee system is likely to be overwhelmed, flooding some of the best agricultural land in the world, poisoning the drinking water with pesticides, manure, and other chemicals of up to 22 million Californians.
- 1.5 million people would need to be evacuated. The most populous areas affected are parts of the San Francisco Bay Area, and Orange, Los Angeles, and San Diego counties.
Effects of 1861-62 storm
- California went bankrupt after a third of California’s taxable land was wiped out
- Lakes formed in the Mojave Desert and Los Angeles Basin.
- Even larger storms occurred in 212, 440, 603, 1029, 1418, and 1605.
References
Achenbach, J. 13 May 2011. The Century of Disasters. Meltdowns. Floods. Tornadoes. Oil spills. Grid crashes. Why more and more things seem to be going wrong, and what we can do about it. Slate.com
Amadeo, K. Aug 31, 2017. Hurricane Katrina Facts: Damage and Costs. The Balance.
Bwarie, J. 2011. ARkStorm: California’s Other “Big One”. USGS.
Balassone, M. 25 Feb 2011. USC Economist: California Superstorm Would be Costliest U.S. Disaster. USC News.
Cahill, Scott. August 20, 2017. Collapse Risk At The Oroville Dam Is Still Unacceptably High. Bungled repairs and new concerns at the tallest US dam. Peak prosperity podcast.
Dettinger, M. June 1, 2011. Climate Change, Atmospheric Rivers, and Floods in California – A Multimodel Analysis of Storm Frequency and Magnitude Changes (pages 514–523). Journal of the American Water Resources Association.
Dettinger, M., Ingram, B. L. 2013. The Coming Megafloods Huge flows of vapor in the atmosphere, dubbed “atmospheric rivers,” have unleashed massive floods every 200 years, and climate change could bring more of them. Scientific American.
Lankgree, G. September 1, 2017. Hurricane Harvey Could Cost $190 Billion, Topping Hurricane Katrina. Newsweek.
Kollewe, J. August 29, 2017. Total Harvey cost could be as high as $100 bn, says insurance expert. The Guardian.
Mackenzie, D. March 30, 3013. Skyfall. NewScientist.
NRA (Natural Resources Agency). 2013. Safeguarding California: reducing climate risk. An update to the 2009 California climate adaptation strategy. Public draft. State of California. 289 pp.
Schlosberg J et al (2020) California’s ‘trillion dollar’ mega disaster no one is talking about. ABC News.
SD. January 18, 2011. ARkStorm: California’s other ‘Big One’. ScienceDaily.
Sullivan, C. Jan 20, 2011. 200-Year Flood in Calif. More Devastating Than Major Quake, USGS Says. New York Times.
Swain DL et al (2018) Increasing precipitation volatility in twenty-first-century California. Nature Climate Change.
USC. March 8 2011. California Superstorm Would Be Costliest US Disaster. ScienceDaily.com (source: University of Southern California)
USGS. 2011. Overview of the ARkStrom Scenario. Open file report 2010-1312. 201 pages. United States Geological Survey and US Dept of the Interior.
Upton, J. 2016. Climate Change Could Bring Bigger, Wetter Storms to California, Study Says. KQED news. Original paper: Hagos, S. M., et al. 6 Feb 2016. A projection of changes in landfalling atmospheric river frequency and extreme precipitation over western North America from the Large Ensemble CESM simulations. Geophysical research letters.
Appendix A. crop and livestock estimated damages by county.
USGS & US Dept of the Interior. 2011. Overview of the ARkStrom Scenario. Open file report 2010-1312. 77 pages.