Increasing the fuel efficiency of the cars we drive is a great cause.
But it's not enough. We have to go a giant step further with sharp cuts in how far, and how often, we drive. If we don't, there's virtually no chance we can reduce our cars' massive greenhouse-gas emissions - now responsible for 45 percent of automobile carbon emissions worldwide.
The message and the math are incorporated in a just-released report - "Growing Cooler" - issued by the prestigious Urban Land Institute in collaboration with Smart Growth America and allied organizations.
The problem is complex and fierce. There's now broad agreement among scientists that to restrain an upward spiral in global warming - with dangerously rising seas and spreading deserts - global temperature rise must be limited to 2 degrees Celsius. And that to reach that goal, the U.S., up to now the world's champion polluter, must cut its carbon-dioxide emissions between 60 percent to 80 percent by 2050, relative to their 1990 levels.
The authors projected that even if stiffer new fuel-economy standards currently now before Congress are approved, and even if there's progress on hybrid cars and lower-carbon fuels, the nation's transportation-related CO2 emissions in 2030 would be 12 percent above the 2005 level and 40 percent above the 1990 level, casting a deep shadow across the 2050 goal.
So is there any way out? Yes, they reply: Cut back sharply on the miles we drive our vehicles. Since 1980, total miles driven by Americans has grown three times faster than the rise in our population, even twice as fast as vehicle registrations. The vast majority of new development is laid out assuming people will use cars for virtually all trips. Homes have been built ever farther from workplaces. Shopping malls, big retail boxes, office parks and new schools are routinely built without a thought to pedestrians or public transit. The net result: more and longer auto trips, most often driving alone.
But what if we switched to develop more compactly? Surveys show at least a third of us would now prefer more-compact communities in which homes, town centers, shops, parks and schools are in walking or biking distance. It's true that many young families feel obliged to "drive till you qualify" - ever-longer commutes for an affordable mortgage.
"Growing Cooler" offers a "smart growth" recipe of walkable, transit-served and "New Urbanist"-style developments, more-compact new housing, shops and offices filling in vacant lots or sites of failing shopping centers rather than replacing forests or farmland. In such developments, people typically drive 20 percent to 40 percent less than on the suburban edge.
The chance for change could be great because there'll likely be a massive two-thirds turnover of the nation's building stock by 2050.
If only 60 percent of that development is clustered in compact, mixed-use areas, the "Growing Cooler" authors calculate vehicle miles traveled would be cut back enough to slash transportation-related greenhouse-gas emissions by a significant 7 percent to 10 percent.
But declaring such a vision and achieving it won't be easy. As Rick Cole, urban author and city manager of Ventura, Calif., observes, our predominant dream "remains a suburban one, enforced by rigid zoning codes and churned out by developers on autopilot."
And changing it will churn the political waters. Cole cites the political firestorm set off when California Attorney General Jerry Brown sued rapidly growing San Bernardino County and pressured other counties to show how their development plans will reduce greenhouse gases. Brown's San Bernardino suit spurred opposition from the building industry and the state Chamber of Commerce. But the county recently did agree to devise strategies to reduce CO2 emissions.
Beyond court suits, Cole suggests that cities themselves must be more proactive by finding room for more people in their already developed footprint, and assuring prospective new residents the attractions Americans are sure to demand: "far greener urban building, far better urban schools, far more attractive urban parks, far safer urban streets."
Plus, I'd add, develop the same kind of comprehensive, reliable rail and bus systems that Europe and Japan offer - real alternatives to the private car.
Carbon-saving communities may be a 21st-century imperative. But the transition to them is likely to be one of the most challenging adjustments Americans have ever made.
Neal Peirce's column appears alternate Mondays on editorial pages of The Times. His e-mail address is email@example.com
© 2007, Washington Post Writers Group