California and the Southwest have a long history of drought. Some Southwest droughts lasted 100 years. Worse, the 20th Century may have been unusually wet. Yet water infrastructures were built and planning was done assuming droughts, if any, would be brief. This was almost certainly a short-sighted, irresponsible approach. These droughts, since they have occurred in the past when far few humans were in the Southwest, have little to do with human-based climate change. Arguing whether or not climate change is a factor in the current drought seems to me to be mostly irrelevant. The more important issues are dealing with drought now and planning in advance for future droughts that surely will come.
It’s getting dire, and this drought may be less of a drought and more the beginning of a dry spell.
As 2013 came to a close, the media dutifully reported that the year had been the driest in California since records began to be kept in the 1840s. UC Berkeley paleoclimatologist B. Lynn Ingram didn’t think the news stories captured the seriousness of the situation.
“This could potentially be the driest water year in 500 years,” says Ingram, a professor of earth and planetary science and geography.
Ingram co-authored The West without Water: What Past Floods, Droughts, and Other Climatic Clues Tell Us about Tomorrow which explores these issues in detail.
Climate change is indeed a problem and may be making a potentially bad situation worse. However, killer droughts (like the one that probably wiped out the Anasazi, were not due to human-caused global warming. This means reversing the effects of climate change will not end long droughts in the Southwest.
You mentioned global warming. Is what we’re seeing consistent with the predictions that have been made about how climate change could affect California?
Yes. We’ve already started having a decreased snow pack and increased wild fire frequency. And we’ve been warming, and it’s gotten drier. With Pacific Decadal Oscillation [the ever-changing temperature of surface water in the North Pacific Ocean], every 20 or 30 years we go in and out of these positive and negative shifts that affect precipitation and temperature. But now we’re entering a period where it looks like we’re getting drier even though it doesn’t necessarily correspond to that cycle. It looks like a trend. It’s warming and drying, and that’s definitely a big concern for Western states.