What can we do to live sustainably in an uncertain world? Here, in a desert city averaging eight inches of rainfall annually yet carpeted with golf courses and dotted with swimming pools, it is an especially relevant question. Unfortunately, Phoenix’s tangle of laws, rights and agreements, which range from individual wells to regional compacts, also make it a difficult one to answer. Add global climate change to the equation and you have a recipe for policy paralysis.

Breaking that paralysis means finding ways to make decisions under uncertainty. It sounds painfully difficult, but perhaps there is a common-sense approach that could get the valley on the right track right now. All it requires is balancing the budget and hedging our bets.

“I think businesspeople shake their heads at this because, who doesn’t understand the need to manage your stock portfolio in the face of an uncertain economy?” says Patricia Gober, co-director of Decision Center for a Desert City. “Businesses do that. Individuals do that. Why shouldn’t we do it with natural resources?”

People live with uncertainty every day. Some live within their means, saving for the future, while others max out their credit cards. Phoenix, unfortunately, falls into the latter category, living the lush life off non-Arizona water. One major step in the right direction, then, might be to cut up the proverbial credit cards and become a desert city again.

It might not be as hard as it sounds.

“In Phoenix, depending on the municipality, between 60 and 70 percent of home water use is outdoor water use,” Gober says. “We can xeriscape our yards and have tremendous impact before ever influencing the way people take showers, flush their toilets or wash their dishes.”

Xeriscaping would not only remove water-guzzling plants, it would also decrease water use by getting rid of high-tech sprinkler systems, which tend to be insensitive to variations in water requirements over time. Getting rid of swimming pools, which annually lose the equivalent of their total volume through evaporation, could also be a big help. A smarter alternative might include community pools in new residential developments.

Another more controversial way to reduce outdoor water use might be to infill the city. Increasing population density, Gober says, would decrease per-capita outdoor water use.

The problem with this option is its potential impact on the urban heat island—the area of locally higher temperature associated with urban areas. Increasing the amount of heat-absorbing building materials while shrinking swaths of open area could worsen heat island effects, as could the amplified insulation and wind resistance caused by taller buildings. If so, they could offset or overwhelm any potential gains from infill.

“How does that balance work? We don’t know,” Gober says. “If you plant trees, does that mitigate the urban heat island effect in central Phoenix? How much water would it take to maintain the vegetation versus how much water would it save to have a cooler environment? These are just a few of the real policy questions that need to be answered for Phoenix to sustain itself in uncertain times.”

Continuing investigations into the ideal urban balance, along with future developments in building materials and green technologies, could bring Phoenix closer to becoming a “sustainable city.” In the meantime, Gober says, finding smarter growth strategies and managing our own water budgets are a step in the right direction.

Nick Gerbis

ASU Media Relations

ngerbis@asu.edu

(480) 965-9690

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