Saturday, December 6, 2014

Of Floods and Droughts - Past, Present and Yet to Come

I just finished reading The West without Water by B. Lynn Ingram and Frances Malamud-Roam.  For the most part, the book is an interesting look at 20,000 years of climate history in the American West, with an eye towards predicting the impacts of impending climate change.  While accounts of prehistoric and historic droughts, floods and other extreme weather events are interesting and informative, I found myself disappointed by the tired, disproven (at least from my perspective) anti-agriculture solutions offered in the book's conclusion.  While the science behind the examination of the historic climate record seems thorough, I find the lack of scientific rigor applied to the recommended solutions.

The majority of the book is devoted to a rigorous review of the scientific evidence for variations in the climate of the American West in the last 20,000 years.  The opening chapters review much of the written history of California and the West with respect to climate - especially the 1861-1862 floods in California and the "Great Droughts of the Twentieth Century."  The authors provide an excellent account of the 1861-1862 floods - the loss of life and property were devastating.  The authors make the case that such an event could happen again - and that we are ill-prepared in California (with nearly 40 million residents, some of whom live in flood plains). I was most struck by an account from the January 11, 1862 edition of the Nevada City Democrat that "reported that Native Americans left Marysville for the Sierra foothills a week before the large flood, predicting higher water than at any time since the region had been settled by European-American pioneers." (p. 38).

Part Two reviews the geologic, climatic and biologic record of the Holocene Epic - including the "Long Drought" of the Mid-Holocene, the "Great 'Medieval Drought'," and the "Little Ice Age of the 17th and 18th Centuries.  In this well-researched section of the book, the authors describe the tremendous variability in the climate of the American West, as well as the cycles and oscillations behind this variability (including El Nino, La Nina and the Pacific Decadal Oscillation).  Ingram and Malamud-Roam succinctly relate these prehistoric and historic climatic variations to the possible impacts of impending climate change.  While this section is especially well written, perhaps the most important perspective is offered in a quote on the book's dust jacket.  James Lawrence Powell, author of Dead Pool: Lake Powell, Global Warming, and the Future of Water in the West, says, "Earth's climate has changed before but always on a geological time scale.  By burning millions of years' worth of fossil fuels in a couple of centuries, humans have now forced atmospheric change onto our time scale."

This sentence sums up my worry about climate change.  Based on what I've read (in this book and others), I believe that earth's climate has always been variable.  For the most part, it seems, past climatic changes have happened at a pace that has allowed the environment - plants, animals (and to a lesser extent, humans) to adjust.  By speeding up the carbon cycle by burning fossil fuel, I fear we've compressed climate change (which has generally occurred on a geological time scale of tens- to hundreds-of-thousands of years) into our own lifetimes.  While our current drought is frightening, to be sure, I'm more frightened by the evidence that 2013 and 2014 have been among the warmest years in recorded human history.  Change seems to be gathering momentum.

As much as I found the first two sections of this book interesting and well-written, I was tremendously disappointed by the ill-informed and seemingly un-researched indictment of agriculture in the last section.  To summarize, the authors seem to believe that if we'd simply stop raising cattle and start planting high-value permanent crops (like nuts, fruits and grape) that use high-tech irrigation systems, we'd solve most of our water problems.  I take issue with this perspective for two reasons.

First, the science behind these assertions is far from settled.  The authors suggest that a six-ounce steak requires 2,600 gallons of water to produce.  Unfortunately, their bibliography for this chapter does not provide any direct references for this number.  Despite this oversight, there is current research from UC Davis that provides an very different picture.  According to research published in the Journal of Animal Science by JL Beckett and JW Oltjen in 1993, this six-ounce steak takes just 157 gallons for applied irrigation water to produce.  Rangeland livestock production, in my experience, is an important way of producing meat, milk and fiber from vegetation grown with rainfall on land that otherwise wouldn't produce food.

The second assertion - that we need to move away from "thirsty" row and field crops (like alfalfa and rice) and into higher value permanent crops (like almonds and grapes) seems to have been disproven during our most recent drought.  In a normal year, these row crops may take a bit more water to grow.  In dry years (like 2014, for example) farmers can elect not to grow them.  Permanent crops, however, are less forgiving.  Many farmers who made the transition to high value crops in the last 20 years drilled new and/or deeper wells this year to keep these trees and vines alive - they couldn't fallow orchards or vineyards in the current drought.

While my objections to these assertions obviously demonstrate my bias towards food production as the most important human use of water beyond drinking water, I think the authors' bias demonstrates a more troubling problem.  While much of the research into past climate variation and current climate impacts is rigorous, many of the recommended solutions appear to by philosophically or politically motivated.  The ultimate solutions in my opinion will require ALL of us to change the ways we live and use resources.  Agriculture needs to come to the table, but so do urban areas, suburban homeowners, environmentalists - everyone!  We'll all need to adapt.

Read the book - it's worth your investment of time - but read it critically.

No comments:

Post a Comment