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25Jan 2013

UPDATED* Not Much Ink for ARkStorms that could wreck the West Coast, but Scientific American spells out the near-Noachian peril

UPDATED*  Not Much Ink for ARkStorms that could wreck the West Coast, but Scientific American spells out the near-Noachian peril

  It is not that the great flood of 1861-2 has been forgotten in California. It is in the history books and is a staple lesson in media feature stories on the state's water problems, floods, and such all. I've mentioned this epic onslaught in stories once in awhile, and always think its most amazing aspect is not that it flooded Sacramento and a good deal of the central valley (there weren't many towns out there then), but that SF Bay was so engorged by river runoff that it filled beyond the normal high tide level. That meant the Golden Gate flowed outward day and night for a stretch, the bay became a muddy but near-fresh water lake. Given the power of the tide's flood at the gate, it is astounding that enough rain could fall to stop it.

   This morning I learned the the USGS has a huge new report out on ARkStorms - newly recognized monster versions of a West Coast weather phenomenon recently in the news, the Atmospheric River. That was in media accounts in the late fall as a train of rain shellacked California. The latest came to me via a short posting on the Energy Collective website, by a poet-turned-Earth-activist named David Lewis. Lewis's piece has the nifty hed, "California's "Other Big One": A Historical Flood?" That article in turn referrred to a short piece in the online media outlet LA Observed by Kevin Roderick.

    One finds relatively little on ARkStorms in news searches. This ought to change. Both of the postings behind the links in hte previoius paragraph refer to a strong article in the January Scientific American by a geographer at UC Berkeley and a USGS hydrologist who works from offices at the Scripps Institution of Oceanography. A sidebar with it, a vivid discription of the 1861-62 water onslaught, is gripping. 

   More important for science writers, particularly those that follow climate change and the weirding of weather, is another pub mentioned in these two postings:

    This is scary reading. The worst natural disaster looming over the US, period? And it happens not often, but inevitably and on a once per century or so rate? And the 19th century version that struck CA was but a middling-sized example? And climate models suggest they will become larger as time goes by under accepted climate change projections?

   There has not been much real coverage of this whole new category of things to worry about that could devastate the West Coast and probably put the national economy into a serious slide. But not much does not mean none.

   Other Stories:

   I suspect that several other general interest media have written this up in the last year or so, but couldn't find examples. Send some in and I'll add them to the list (do so via Suggest a Story). The December AGU meeting included sessions on atmospheric rivers. Perhaps some of those produced coverage I missed. 


  • Scientific American - Mark Fischetti: New Observatories Will Warn Public about "Atmospheric River" Floods ; Fischetti was editor of the Sci Am magazine report on ARkRivers - which was then just coming out - and also covered the AGU meeting whence this story comes (and to which he tips us off, thank you sir). As interesting as is the story, the comments give it a needed political and sociological context- including a ranting contrarian's spittle and some smart back and forth. 

By the way, the ARk in ARkStorm is for Atmospheric River k-for-1,000 or the rough time scale in years on which such giant parades of precipitation start to look common. (Nope! See comments. The k is not for 1000 yrs but a new scale system for storm magnitude.) 






It turns out that the 1,000 in ARkStorm is not about time scale. In fact, it's almost the opposite: The 1,000 denotes a solution to the deep faults of time scale ratings.

The problem with frequency ratings is that extreme weather events are happening more often. The frequency is both increasing and becoming much more erratic. Studies of silt layers give clues that the past few thousand years were much more frequency-predictable, so using such a scale made sense until recently. But the meteorological future is expected to be a big mess. As a result, time-scale ratings have been essentially abandoned for serious predictive science.

The 1,000 is for the new storm rating scale that the USGS hopes will come of their ARkStorm project, setting 1,000 at the level of what they believe the 1861-62 storm reached.

This is an ambitious task, and a very interesting one, since it requires formulating a single metric that expresses everything from extent, duration and severity of the storm to destructive capacity, temperature fluctuation, wind and precipitation, among other factors. The hardest part is comparing storms that are measurably similar in one way--such as wind or rain--at a given location but very different at another location.

One of the most impressive things about 1861-62 was the area it covered (from Washington to Southern California and well inland) delivering severe conditions. Should a storm that hits a narrower area but has more hail, for instance, be rated less, more or the same? The USGS team has a daunting task ahead.

Thanks for keeping up with this topic. Until three years ago, I was one of a very small number researching this from the science history perspective. Now there's much evidence of active research, though most is centered around the immeasurably giant task of hazard mitigation (to say nothing of the survivalist "preppers") rather than general education about climate and historical geography, which is my interest.

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