Mayors Take the Lead

Many cities are also encouraging private individuals and taxi companies to switch to hybrids and other high-efficiency vehicles by offering a variety of incentives. In Salt Lake City, says Mayor Rocky Anderson, "the transportation department will put a decal in your rear window, and you can park at any city meters without ever having to pay." And in Boston the Massachusetts Port Authority, which runs Logan airport, is about to start giving hybrid taxis two passes per shift allowing them to cut to the front of the passenger-pickup line. But the very existence of a program for hybrid taxis in Boston is due at least in part to a private initiative by architect John Moore, who last year got permission to follow a standard cab around town for a day in a borrowed Ford Escape hybrid. At the end of the day, the hybrid had used just 3.5 gallons of gas, versus 10.2 for the cab—and with fewer emissions. Moore's experiment helped persuade the city to approve hybrid cabs, a shift that could ultimately translate into greater reductions of greenhouse gases than for most autos, since cabs are on the road all day.

Better yet are trips not taken at all—at least not in privately owned cars. Des Moines, Iowa, has installed bike racks on the front of buses to make longer, car-free commutes more practical, and it has sponsored contests to design artistic bike racks for public spaces. In addition, a growing number of cities have seen the arrival of car-sharing programs like Flexcar in Seattle. For a $35 annual fee, you can go online and reserve cars parked at convenient locations. "Like a cash machine, there should always be one within a couple blocks," says spokesman John Williams. You pay $9 per hour, but the company covers gas, insurance and parking in designated spots. It's so convenient that about half the members end up selling an existing car or avoid buying a new one.

Vibrant Downtowns

New York is the most energy-efficient city in the nation, since millions of residents live in densely packed apartment buildings and rely on walking or public transit for most of their transportation needs. "New Yorkers use half the energy per capita as residents of other cities," says Deputy Mayor Dan Doctoroff.

No wonder cities across the country are trying to attract residents back downtown to live, not just work. In Miami, the city code and zoning laws are being overhauled for that very purpose. "Miami was developed haphazardly by engineers whose only interest was in making it easier for cars, so they built broad roads and narrow sidewalks," says Mayor Manny Diaz. "We want to change that, to have wide sidewalks, with shade trees and parks that create a pedestrian feel." Admittedly, the plan will take decades to implement, but Diaz seems committed to a broad range of shorter-term changes, too, including cleaning up city waterways and building green buildings. "We're on the front line of global climate change here," he says. "The water level doesn't have to rise too much for us to be riding around Miami in canoes."

The greening of city centers isn't just metaphorical. In Chicago, city officials have mapped the "heat islands," where asphalt and black roofs absorb heat and raise the city's overall temperature. These areas are then planted with trees—400,000 to date. "Trees are like big air conditioners," says Environment Commissioner Sadhu Johnston. They lower the temperature, filter air, remove carbon dioxide, absorb storm water and provide shade and beauty. (They even boost the economy. "Research has shown that people are willing to spend up to 12 percent more on a product if they're shopping in a district with mature trees," thanks to the pleasant ambience of the neighborhood, says Johnston.)

At Chicago's Center for Green Technology, the city also runs free programs on topics like planting green roofs, which are actual plots of grass on roofs. They absorb storm water, reduce heat loss in winter and help cool buildings in summer. "We run green-roof test plots to see how much they bring down the temperature," says Johnston. The verdict: a green roof can reduce the surface temperature of a summer-sun-drenched roof from 170 degrees to just 80 to 90 degrees. Chicago has 300 such roofs already built or under development.