Waiting for the 2014 Monsoon Rains

In a few days the summer solstice will be here, and Tucson will be at its hottest and driest. Though we had a few drops of rain the other day, the monsoon rains are nowhere in sight. The birds and animals around me all seem, like me, to be waiting for the rains. And these times of long dry heat may be getting worse in the Desert Southwest (as I noted in my previous blog post) due to climate change.

Desert cottontails, desert spiny lizard, and antelope squirrel
 (click on image to see a larger version)

And as if the dry heat isn't bad enough right now, we in the Southwest are increasingly vulnerable because of our limited water resources. Last Sunday the front page of the Arizona Daily Star featured the story “Tucson is warned of water shortage.” According to Star reporter Tony Davis, the state agency that operates the Central Arizona Project has, for the first time, warned that water shortages could affect Tucson and Phoenix in as little as five years. Though shortages will probably not come that soon, we are still dealing with a combination of drought, growing demand for water, and declining water levels in Lake Mead. Between now and 2026 the likelihood of CAP shortages is 17-29% in a given year. The outcome depends on weather, especially the “impacts of climate change.”

Though Tucsonans have been cutting back on water use (total use sank to 1989 levels last year even though the city has continued to grow), these shortages have been brought about partly by the so-called mega-drought, which is now in its 15th year. Drought been a major factor in reducing Lake Mead from 91% full in 2000 to 45% full today, though there is also a “structural deficit” that existed before the drought started. In other words, in a typical year more water is taken out of Lake Mead than is returned to it. Brad Udall, whose father Arizona Rep. Morris Udall helped extend CAP to Tucson, calls the river’s situation “a ticking time bomb.” He said that, because of continued overuse of water in the West and drought worsened by climate change “there is a cancer on our water-management systems now. It might be slow-growing or fast-growing, but we can’t ignore it and we need to deal with it.” Doug Kennedy, director of the University of Colorado’s Western water policy program says, “Demand on the river caught up with supply around 2000. No one noticed, but the drought also started right there, and (Lake Mead) started dropping like a rock.”

Also on June 15 the Palm Springs, California, paper The Desert Sun featured the third article in its series Scorched Earth: How Climate Change is Altering the Deserts of the Southwest. In this piece called “Vanishing water: An already strained water supply, threatened by climate change," reporter Ian James notes that Lake Mead, the biggest reservoir in the U.S. is dropping one foot each week. Though droughts and even mega-droughts have long been part of the cycle of the Colorado, those fluctuations are now occurring alongside global warming, which puts new pressures on our inadequate water supply. James says scientists aren't sure to what degree climate change is influencing the natural cycle of droughts in the West, but they do know that "hotter temperatures across the West have led to less mountain snowpack and earlier melting of snow in the spring. More of the snow and rain that does fall is evaporating due to warmer temperatures, and that diminishes the flows of water into the Colorado River..." The article includes a chart called "Water supply and water use in the Colorado River Basin," which shows that water use began to exceed water supply during the past decade. There is also a video by Richard Lui and Marilyn Chung ("As Lake Mead declines, climate change poses risks") in which you can see Lake Mead’s earlier water level marked by a white mineral ring and can easily see how much lower the lake's level is compared to 14 years ago. John Entsminger of the Southern Nevada Water Authority says about Lake Mead "That's the bank account for 25 million people," and he says it can hold two full years of the Colorado's flow and now holds only one year's worth.

What will happen to our water supply depends in part on what will happen to our climate, and as is the case with the starting date of the monsoon rains, it's very hard to predict...