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April 2015 P R A C T I C A L W I N E R Y & V I N E YA R D 69 B O O K E X C E R P T The WEST Without WATER climate underscore that, over the past 150 years, nature has dealt the west- ern United States a relatively benign hand. If the decade- to century-long cli- mate extremes written about in this book should revisit the region, modern society will be forced to make dramatic changes in the way we live. Over the past century, society in the West has followed an unsustainable pat- tern of water use, leaving us more vulner- able each year as we head into a climatic future we cannot control. The explod- ing population in the region has been made possible through extensive water development, with dams and aqueducts controlling the distribution of water and buffering the dry years. Nevertheless, we cannot stop droughts from happen- ing. The West is drying, even though water continues to be delivered to our faucets. Key questions probably keep regional water managers awake at night, among them: How bad can it get? How prolonged and severe the droughts? How massive the floods? Lessons from the past The truism that history repeats itself applies not just to the affairs of human- kind but to climate as well. The climate history of the past 20,000 years reveals that the American West has been plagued by deep and prolonged droughts, as well as by enormous floods, on a fairly regular basis. Paleoclimate records from across the region, extracted from many sources discussed in this book — tree rings, sedi- ment cores, lake levels and sediment As shown throughout this book, the American West faces a climatic future that is predicted to become generally warmer and drier, with deeper droughts interspersed with larger and more fre- quent floods. Scientists believe these shifts may have already begun, since the region is experiencing more extreme weather. Only time will tell, but green- house gas–induced warming may be at the root. Reducing the uncertainty of future climate predictions requires an in-depth understanding of the natural patterns and range of climate, including the fluc- tuations of conditions experienced over the millennia prior to human-caused greenhouse warming. As discussed in the preceding chapters, a substantial body of research shows that the so- called "normal" range of past climate is enormously broad. Records of long-term geochemistry, among others — have been compiled over the years to produce this history. Although some questions remain unanswered, the records have informed scientists of the range of climate condi- tions the region has experienced, includ- ing the frequency and magnitude of extreme climate events. These extreme events far exceed those experienced over the past century and a half. How likely are such events to recur, and are we pre- pared for these events today? Droughts During past periods of climatic warming, such as occurred during the mid-Holo- cene and again in the late Holocene, condi- tions throughout the West tended toward increasing dryness, with droughts that could stretch out for centuries. Research from California and the Great Basin, for example, shows that the mid-Holocene was dry for nearly 1,400 years. Humans occupied the American West during this time, and the archaeological record shows that the mid-Holocene warming coincided with mass migrations of native populations from the desert interiors of the West to the coastal regions. This long episode of warmer and drier climate was followed by the Neoglacial — a period of cooler and wetter climate. In the late Holocene, beginning approximately 1,800 years ago, drying conditions returned, peaking during a particularly dry period from AD 900 to 1400 (the so-called Medieval Climate Anomaly). Prolonged droughts were a fixture during this drier millennium, as were intermittent floods. Combined, B. Lynn Ingram and Frances Malamud- Roam BY The following is an excerpt from The West Without Water, a 280-page book avail- able from the University of California Press. Chapter 14: What the past tells us about tomorrow If future generations are to remember us with gratitude rather than contempt, we must leave them more than the miracles of technology. We must leave them a glimpse of the world as it was in the beginning, not just after we got through with it. – President Lyndon B. Johnson (said while signing the Wilderness Act, 1964) Abstract The West Without Water documents 20,000 years in the tumultuous climate of the American West, with tales of past droughts and deluges as well as predictions about the impacts of future climate change on water resources. Looking at the region's current water crisis from the perspective of climate history, the authors ask the central questions: What is the "normal" climate for the West? Can we count on the benign climate of the past century to continue into the future? The West Without Water merges climate research with paleoclimate research and introduces readers to key discoveries in cracking the secrets of the region's past. The book describes how droughts and catastrophic floods have plagued the West with regularity during the past 2,000 years and recounts the most disastrous events in the recorded history of California and the West, including the megaflood of 1861–62. The authors show that, although the western states have temporarily buffered themselves from harsh climatic swings by building dams and reservoirs, and by making other changes to the natural landscape, they may be unprepared for the effects of climate changes that are occurring now and may continue for hundreds of years into the future. The authors argue that it is time to face the realities of the past and prepare for a future in which fresh water may be less reliably available.