The West Without Water

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The West Without Water (Sinclair & Co., Sep 6, 2014):

The West Without Water: An Interview with Dr. B. Lynn Ingram

Dr. B. Lynn Ingram is a professor in the Department of Earth and Planetary Science at UC Berkeley, California. The primary goal of her research is to assess how climates and environments have changed over the past several thousand years based on the geochemical and sedimentologic analysis of aquatic sediments and archaeological deposits, with a particular focus on the US West.

She is the co-author of “The West without Water: What Past Floods, Droughts, and Other Climatic Clues Tell Us about Tomorrow” together with Dr. Frances Malamud-Roam, which received great reviews.

In this interview, Dr. Ingram shares her thoughts on the current drought in the US Southwest within the larger climate record and potential implications for the future.

E. Tavares: Thank you for sharing your thoughts with us today. Your research focuses on long-range geoclimatic trends using a broad sample of historical records. In this sense, “The West without Water”, which we vividly recommend reading, provides a very grounded perspective on the weather outlook for the US Southwest going forward. So let’s start there. What prompted you to write this book?

L. Ingram: My co-author and I decided to write this book because our findings, and those of our colleagues, were all showing that over the past several thousand years, California and the West have experienced extremes in climate that we have not seen in modern history – the past 150 years or so. Floods and droughts far more catastrophic than we can even imagine. We felt it was important to bring these findings to the attention of the broader public, as these events tend to repeat themselves. So we need to prepare, just as we prepare for large earthquakes in California.

ET: When you say “West”, which regions are you referring to?

LI: In the book we focus on the climate history of California and the Southwest, but also bring in examples and comparisons with other western states as appropriate (such as Oregon and Washington, Nevada, Utah, etc.), as the entire region experiences similar storms and is controlled by similar climate that originates in the Pacific Ocean.

ET: What type of evidence have you used in reaching your conclusions? How accurate are these records?

LI: In the book we bring together many lines of evidence, ranging from tree-ring records to sediment cored from beneath lakes, estuaries, and the ocean. Paleoclimatologists – those that study past climate change using geologic evidence – study various aspects of these cores, including the fossils in them, the chemistry of the fossils and the sediments, and pollen and charcoal remains. The charcoal provides evidence about past wildfires. The archaeological record also contains important clues about past climate and environments and how they impacted human populations.

ET: Can you walk us through some of the major climatic events of the past thousand years in that part of the US? How unusual was the 20 century in that context?

LI: We had a relatively dry period during the Medieval Warm Period, 900-1400AD. There were several prolonged periods of drought that lasted decades to over a century during that time. That period was followed by a cooler, wetter period (the Little Ice Age) that continued until the 19 century. However, the tree-ring records suggest that the 20 century was unusually wet, meaning we had fewer droughts on average than the previous 1000 years.

ET: Based on what you just described, what the current drought may be telling us is that we could be seeing the start of a decadal “mean reversion” to much drier conditions going forward. Is this correct?

LI: Yes – actually the past decade in California and the West has been pretty dry, and the concern is that these climate conditions could continue for several more decades. We’ve seen these broader cycles of wet-dry in the past.

ET: And what drives the long-term climate variability in the West?

LI: Over the long-term, natural climate variations are driven by a number of factors, including the ocean temperatures in the north Pacific (the so-called “Pacific Decadal Oscillation”), the El Nino Southern Oscillation, sunspots and even slight changes in the earth’s orbit over thousands of years. Volcanic eruptions can also impact climate. The human-caused increase in greenhouse gases is also impacting our climate, on top of those natural causes, and warming will have a number of affects, including reduced snowpack, drier soils and vegetations and increased wildfires.

ET: Presumably there were Native American populations who went through those protracted periods of dryness. How did they manage to survive? Is there anything we can learn from that?

LI: Actually during the medieval droughts, the Ancestral Pueblo or Anasazi civilization that inhabited the four corners region, whose populations had grown during the wetter periods leading up to the droughts, suffered greatly. There is evidence for conflict, disease and finally mass migration out of their region. The native populations in California also had increased violence, malnutrition and abandoned sites in search of water and other resources. We can learn that even during the wetter times we need to prepare for the eventual dry climate that always follows, as that is the nature of our variable climate here.

ET: These findings are quite concerning. Of course we have the benefit of advanced technologies now. Can human intervention help counter the adverse effects of a prolonged drought?

LI: We will surely have to begin some serious adoption of water conservation technologies (like water efficient appliances, recycling of treated wastewater, desalination, etc.) as part of a comprehensive strategy to adapt to water scarcity.

ET: Such measures can be quite unpopular. While your climate research suggests much drier days ahead, people may still think that at some point the rains will come back like they always have. So why ration water now? If you were a political decision-maker, how do you get past that perception and help focus people’s attention on the long-term risks? What should everyone be thinking about right now?

LI: We have still been using more water than the supply – in California each year we use about 6 million acre-feet from pumping groundwater, which takes a very long time to replenish. Farmers have been using groundwater with no regulation or monitoring in the Central Valley – drawing down the water table.

As our population grows as it’s expected to, we will need to begin serious water conservation and recycling even in the absence of a prolonged drought. This will clearly take a comprehensive plan that involves everyone. A recent analysis by the Pacific Institute outlines water management strategies that could potentially conserve 14 million acre-feet of water per year, which would be hugely beneficial (1).

ET: If you had to ascribe a probability of severely dry decades in the West occurring over the foreseeable future, what would it be?

LI: A team of researchers have analyzed past and present climate change and shown that there is a 50 to 60 percent chance of a 35-year drought occurring in the West.

ET: That’s a very high probability! And as you look at the historical record, what is the worst case scenario for the region? California in particular is such an important state for the US and indeed the world, so the consequences of a prolonged drought could be far reaching. As a state resident, what keeps you up at night? What other states could also be impacted?

LI: The worst case scenario is a repeat of the medieval droughts, which would primarily impact California and the Southwest. The past decade has been very dry in this region, and if it continues for more decades, that would be very difficult.

I also worry about a mega-flood hitting the region, as we’ve seen every one to two centuries. The last one was in 1861-62, and filled the entire Central Valley (350 miles long and 20 miles wide) with water 20 feet deep. This was caused by 43 days of rain from atmospheric river storms.

ET: And with that, here’s my last question. Are you planning to move out of California at some point? Where would you move to? And if it comes to that, which we hope not, what is the signal for people to start getting out of Dodge (perhaps literally in this case)?

LI: I love California too much to leave! I just hope that if the state begins a serious and comprehensive effort, we will be prepared to make it through the dry periods.

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