Sunday, February 15, 2015

The West Without Water (Again)

This is a repost of a book review from last summer.  Seemed appropriate to do again.

Available at Amazon in hardcover and kindle editions
For those of you with an interest in climate change in the western United States, pick up a copy of The West without Water by B. Lynn Ingram and Frances Malamud-Roam.

It is easy to assume that our knowledge of climate is confined to the so-called instrumented period (extending back about 150 years except at a couple of locations), but geologists, oceanographers, ecologists, and other scientists have learned a great deal about climate change, variability, and extremes  (floods and droughts) through the study of climate proxies – ice cores, tree rings, lake and ocean sediments, and other clues left behind by mother nature.

The West without Water lays out the remarkable story that these climate proxies tell about the climate of the western United States, with emphasis on California and the adjoining southwest region. California is a great setting for this story for three reasons.  First, thanks to its extensive higher-education system, considerable research has been done on past climate change in the state.  Second, California probably experiences a greater range of climate extremes (flooding and drought) than any other state in the nation.  Third, extensive water-resource development to support a population of almost 40 million and an agricultural industry that provides 55% of all fruits and vegetables in the United States, makes California extremely vulnerable to floods and droughts.

As I like to say, we're not adapted to the climate of the past 1000 years, let alone the rapidly warming climate of the next 100 years, and the book lays out the case for this very well.  Using climate proxies, it illustrates that the western U.S. has pretty much had a free pass with regards to climate extremes since western settlement began in the late 1800s.  Since then, the extremes of both droughts and floods, have been far less severe than the so called mega floods and mega droughts found in the paleoclimate record over the past 10,000 years, and the book does a wonderful job describing what we now about these mega floods and droughts and how we've learned about them.

Personally, I found the discussion of megafloods to be quite enthralling.  Although droughts are amongst the costliest natural disasters, being a weather guy, I've always found floods to be far more interesting.  And, in this regard, the extended view of California's past climate is terrifying.

The closest modern experience with megaflooding in the west occurred during the Great Flood of 1861–62.  Likely produced by a series of atmospheric river events over a multi-week period, the Great Flood left the entire Central Valley, an area 250–300 miles long, underwater.  Portions of southern California, including the Mohave Desert, were also inundated.  At the time, California was sparsely populated, but estimates suggest that if a similar flood occurred today, damages and expenses would reach $0.5 to $1 Trillion.  Yes, that's Trillion, with a capital T. (The book actually uses $750 billion, but that somehow doesn't seem to bad, so I've used a range estimate here from other studies).  The West without Water examines these megafloods in depth, and an argument is made that floods as large or larger than the Great Flood of 1861–62 occur with a return interval of 200 years, including an extraordinary event in AD1605 that has been detected in climate proxies throughout California.

One quibble I is that the author's frequently generalize their findings for a region they describe as the American West.  For example, they state that "The American West faces a climate future that is predicted to become generally warmer and drier."  Such a statement is true for the Southwest, but not the Northwest.  I kept wishing that they used American Southwest instead.  Of course, this doesn't mean that the Pacific Northwest won't have it's own share of problems.  There is also a strong emphasis on California, but that seems appropriate given the data available and the extremes of vulnerability.  They do venture inland from time to time, including discussions of flooding in southwest Utah.

The bottom line is The West without Water is an excellent read for anyone interested in learning more about the past climate of California and the southwest and our potential vulnerability to mega droughts and floods.  Available in hardcover and kindle editions at Amazon.

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