The rains had been heavy on and off for weeks, soaking the ground, washing away the soil and undercutting our yard and those of our neighbors. This happened 45 years ago, when we lived on a steep mountain ridge in the Santa Ynez Mountains of Santa Barbara, about 100 miles northwest of Los Angeles.
Where once we had an ample yard, 15 feet of grass now separated our house from the precipitous edge of the slope. That led to anxious nights with images in my mind of our house sliding down the slope while I slept. Although our house never went over the edge, those feelings of anxiety sometimes recur during big storms.
A little research reveals that the worst storm ever recorded in California struck on Christmas Eve of 1861. The rains continued almost nonstop until February 1862, soaking California with almost four times its normal rainfall, and creating enormous brown lakes on the normally dry plains of Southern California. In the Sierra Nevada, the deluges filled rivers, transforming them into raging torrents that swept away entire communities and gold-mining settlements in the foothills.
In California’s enormous Central Valley—a region well more than 300 miles long and 20 miles wide—the floodwaters streaming from the Sierra produced an inland sea, covering farmlands and towns. Sacramento was submerged under 10 feet of brown, debris-laden water, forcing residents to move about the city by boat.
California wasn’t alone in its misery: Diary and newspaper accounts suggest that most of the West Coast, as well as inland areas in Nevada, Utah and Arizona, suffered their worst floods in history.
Then there’s drought. I recall living through the severest drought on record for many Western states, which happened during the winter of 1976-1977. In California, this period is known as “the year with no rain.”
I was a teenager, and for the first time, I had to confront the realization that water was a finite resource. My family had always used water liberally, with little thought about supply, but that year, every drop counted. Washing cars, watering lawns and taking baths or long showers were banned. These “sacrifices” paled in comparison to the far harsher impacts we heard about on the news, faced by farmers with little water, ski areas with no snow, and forests drying and burning.
This bipolar behavior of our Western climate left me wondering what a “normal” climate really was.
Today, I am one of a small cohort of scientists trying to answer that question, by searching for evidence of past droughts and floods, wildfires, periods of warmth and cold and so on, over the geologic past—the period before humans kept records in the West.
If we step back and view our climate history over a very long time period—say, hundreds to thousands of years—we begin to see the forest for the trees. We can pick out extreme events and how often they occur. This natural history is written not in paper and ink, but in the earth itself, in sediment, stone, trees and ice. Like investigators at a crime scene, we try to piece together seemingly random and unrelated clues about our past climate, and eventually, we begin to see patterns.
Our discoveries are occasionally surprising, sometimes unsettling, even anxiety-provoking. Evidence is mounting, for example, that two prolonged droughts, each lasting more than a century, gripped the Southwest during medieval times, about 650 to 1,100 years ago.
Decades-long droughts have also occurred more frequently and fairly regularly, telling us that these dry periods are a normal feature of our climate.
We have also found evidence of previous catastrophic floods in the region, suggesting that the “megaflood” in 1861-1862 was not a freak event. Our studies indicate that huge floods—much larger than we have experienced in the past century—occurred every 100 to 200 years over the past few thousand years.
It’s unsettling to think about the implications of extreme climate events—and the reality that global warming may make severe weather much more frequent and even more extreme. These days, of course, my adult mind can provide diversions, and some people are getting quite skillful at outright denial. This might alleviate unease in the short run, but I know that the best long-term solution is for scientists to prepare everyone living in our Western states for a future of unpredictable and extreme climate change.
B. Lynn Ingram is a contributor to Writers on the Range, a service of High Country News. She is a professor of earth science at the University of California at Berkeley, and author of The West Without Water: What Past Floods, Droughts, and other Climatic Clues Tell Us About Tomorrow.