Mayor Phil Gordon announced an ambitious plan in 2009 to make Phoenix “the greenest city in America.” Though admirable, the plan will have to solve at least two of the metro area’s most daunting environmental problems if it’s to be more than rhetoric—namely air pollution and suburban sprawl.

In winter, a “brown cloud” of dust, car exhaust, and other particulates often hangs over the city for days at a time thanks to the surrounding mountains, which block the wind and trap warmer air near the ground. In summer, strong sunlight and extreme heat interact with chemicals in car exhaust to form ozone, a colorless pollutant that affects breathing and often leads to warnings from health officials that people with respiratory illnesses should stay inside. It’s a problem that defies easy solution in a metro area that sprawls over more than 1,000 square miles and forces residents to drive almost everywhere.

But that’s not the only problem with the way one of America’s fastest-growing cities is planned and built. The new subdivisions, office parks, and shopping malls sprouting up on the edge of town are paving over the desert at the rate of more than an acre per hour. This destroys wildlife habitat and native plants (though damaging or even moving a saguaro cactus without a permit can result in hefty fines and even jail time), not to mention the views of pristine desert that draw so many people to Arizona in the first place.

Water and where to get it has always been a top concern in the desert, but metro Phoenix has fewer problems in this area than might be expected. Rivers and streams that flow out of the mountains to the north and east fill roughly half the metropolis’s water needs, while a 350-mile canal from the Colorado River delivers the other half. Local officials say the billions of dollars spent on this water infrastructure can supply more than the area currently needs, but a long drought could create serious problems.

The complicated legal agreement that apportions water from the Colorado River to states along its banks is actually based on historically high levels of water, and with California at the front of the line, Arizona cities could get very thirsty if the mountain snows that feed all the rivers around the state get much lighter. Draining rivers so completely also creates a slew of environmental problems. Even under current conditions, very little of the water from the Salt and the Gila Rivers makes it to the Colorado, and the mighty river itself now dries up long before it reaches its mouth at the Sea of Cortez.

Another major problem comes from wildfires sparked by lightning, campers, and other human activities. Huge blazes in recent years have charred hundreds of square miles at a time. Though none of the fires have reached Phoenix, Scottsdale, or any of the surrounding suburbs, homes and businesses in small, remote communities are burned nearly every year, and it seems like only a matter of time before some of the northeastern suburbs of metro Phoenix that back up to the Tonto National Forest get hit.

State and local officials are trying to address these problems by changing the way people live and travel in the region. A new light-rail line running through Phoenix, Tempe, and Mesa opened in 2008. It surpassed ridership expectations in its first six months, and it promises to ease congestion and attract more businesses and residents in the neighborhoods it passes through. There’s also an effort afoot to establish the metro area as a major player in the solar-power industry. Abundant sunshine makes the region a shoo-in for production—one of the largest solar-power plants in the country is planned for a landfill outside the city—but many business leaders are hoping for clean solar-manufacturing plants, too.

These will hopefully attract high-paying engineering jobs to a metro area that’s always been big in computer-chip manufacturing and engineering. But they may also help bring the next wave of technology to a place that’s been uniquely affected by it. From the precise levels used by the Hohokam to build ancient irrigation canals from the Salt River to the air-conditioning-inspired real estate boom of the 1950s and ’60s, metro Phoenix has been uniquely affected by new ideas and products—and there’s no reason to think that the future won’t repeat the cycle.