He Who Forgets His History Is Doomed to Repeat It. He Who Never Knew It Is In For Surprises.

Those of us living in urban, western North America live in a relatively young society.   Our kind just haven't been around that long.   Because of that we're unfamiliar with what, in the long run, is "normal" for our locale.   Oh we've heard about the giant quakes that strike every three or four-hundred years but our society is less than two hundred years old and has never experienced one.   We will, one day, and then those of us who survive will duly enter it in the books.    For now, however, it's the stuff of legend.

Consider the prairie.   That has been settled mainly over the past hundred years or so.   The settlers put the grasslands into agricultural production turning it into the breadbasket of our nation.   That led to the establishment of railroads, highways, airports, towns and cities and all the infrastructure that goes with such things.   But we did all this without regard to the history of the prairie.  Only recently did we learn that this region is prone to megadroughts lasting 60-years or more.  60 years?   The fact that, when we showed up, it was prairie grassland made up of some pretty drought-resistant species should have given us pause but didn't.   What we didn't understand that the conditions when we arrived were not normal, not even close.   Our arrival coincided with a century plus-long stretch of unduly wet conditions, perfect for large-scale agriculture.  And so we built a society around that, on false assumptions.

The American southwest is in for its own surprises.  It's running out of water and megadrought is just beginning to set in.   The states in that area are already introducing drastic measures to curb water consumption and that will do a lot to ease the problem - temporarily.   Eventually you reach a baseline threshhold and then you have to depopulate.

Now it's California that's getting a history lesson.   117-researchers got together last week to report that global warming could trigger "superstorms" capable of flooding California's key agricultural zone, the central valley.

A winter storm that brings warm South Pacific air over parts of California, creating an " atmospheric river"   that could bring 10 feet of rain over 40 days, flooding large tracts of the state and bringing flood water to nearly a quarter of the state's homes.

Such a storm could bring water into California at a rate equivalent to that of 50 Mississippi rivers, the climate model projected.

As sensational as that scenario sounds, researchers say it's based in historical reality: Such storms have hit California before, most notably in 1861 and 1862, when floods turned a 300-mile stretch of the Central Valley into a lake. The New York Times reports:

The storms lasted 45 days, creating lakes in parts of the Mojave Desert and, according to a survey account, “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 Gov. Leland Stanford to take a rowboat to his inauguration.”

Today we're witnessing megafloods in Australia, Brazil and Sri Lanka.   While they're triggered by the southern oscillation La Nina event the severity is being attributed, at least in part, to atmospheric warming.