As gas prices soar, some environmentalists see a green lining to the dark cloud of higher costs: People are driving less and buying fewer gas-guzzlers. And that means less global-warming pollution.
"From an environmental perspective, this is a crucial area of change," said Therese Langer of the American Council for an Energy Efficient Economy. "People drive less when the prices are higher, and we are seeing a dramatic shift in purchasing behavior toward more efficient vehicles."
According to the Federal Highway Administration, Americans drove 12 billion fewer miles in the first quarter of this year compared with the same period in 2007, or 2 percent less. That means roughly 9 million fewer metric tons of carbon dioxide and other greenhouse gases puffing from the tailpipes of vehicles, federal data suggest.
The 4.3 percent drop in miles driven during March was the steepest year-over-year decline for any month since the federal government started counting in 1942.
While government figures on vehicle sales aren't available for this year, manufacturers are reporting a significant drop in demand for trucks and SUVs and an increase in sales of high-mileage vehicles. Just last week, General Motors announced that it will be making fewer trucks and SUVs. The company said it might even put its iconic Hummer brand on the auction block.
David Kroodsma of the group Climate Ride, which promotes awareness of global warming, said another "upside" of high gas prices is that motorists might turn to bicycles and other means of transit. "It's good for the environment, because it means less global warming and air pollution. And it's good for land use, because when you take cars off the road, you make cities more pleasant and livable."
But many advocates also lament that the federal government failed to plan for the oil spike by investing in public transportation and other programs that could have reduced the economic pain for working people.
"This is not the right way to go about greenhouse gas reductions - to let oil pricing in Saudi Arabia and the market forces drive up gas prices in a way that hurts poor and middle-class Americans," said Mike Tidwell, a Tacoma Park author and founder of the Chesapeake Climate Action Network.
Langer said it would have been better to avoid the layoffs at GM and the price shock among consumers through smarter public policy. Congress should have been nudging car makers toward smaller and more efficient vehicles by slowly raising vehicle fuel efficiency standards during the 1980s and 1990s, she said.
Instead, the federal government waited three decades before increasing standards for cars in December from a 25 mpg average today to 35 mpg by 2020.
During the delay, American vehicles just got bigger, increasing dependence on foreign fuel.
The owners of hybrid cars - which get up to 50 mpg - have a sense of satisfaction these days. Tidwell said that when he rolls up to the gas pump, he feels smart for having bought a Toyota Prius three years ago.
Back then, he said, people scoffed that only the "lunatic fringe" would pay an extra $5,000 for a hybrid car.
"How smart do Prius drivers look now?" he said.
The average American vehicle produces about 12,100 pounds a year of carbon dioxide, one of the greenhouse gases that cause global warming, according to the Environmental Protection Agency. Cars also emit benzene, a carcinogen, and pollutants including nitrogen oxides that form smog.
Greenhouse-gas emissions from cars and trucks in America have been rising at an average of 1.7 percent a year over the past several years as people have driven longer commutes from farther-flung areas.
Now that trend might be reversing as people drive slightly less, according to the American Council for an Energy Efficient Economy.
Many activists caution that environmental improvements could be brief if oil prices drop and people revert to old habits - or if prices spike so high that they drive the nation to burn more coal or drill in protected wildlife areas.
Others suggest that a sustained rise in gas prices could lead to a shift in development patterns away from suburban sprawl and toward a more European style of living in which people can walk and bike to work.
"The European economy is doing pretty well - it's not like the price of gas has tanked their economy," said Brad Heavner, director of Environment Maryland. "They have been taxing their gasoline and using the money for public transportation."
Dru Schmidt-Perkins, director of an anti-sprawl organization called 1000 Friends of Maryland, said the surge in gas prices probably won't affect people's decisions about where to buy homes unless it's a permanent increase.
"We are seeing more people interested in living closer to work. ... People want to move back into towns and metropolitan areas," she said. "But people can't sell their homes because of the way the real estate market is. They're locked in."
A recent survey by the travel industry suggested that $4-per-gallon gasoline will change behavior only to a point. Twenty-six percent of 1,000 people contacted by phone between May 30 and June 2 said they are cutting back on travel or recreational driving because of gas prices, according to Access America, a Richmond-based travel insurance company.
Twenty one percent said they're consolidating errands. But only 6 percent said they are walking more or biking more, and 4 percent said they are taking more public transportation, according to the company.
"In very suburban areas and rural areas, everything is all spread out, and people don't really have mass transit systems - so people don't have many options," said Mark Cipolletti, spokesman for Access America.
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