Airlines and airplane makers have largely slipped under the radar in the debate over global warming.
But a dispute over a European emissions-trading proposal has caught many carriers and their trade groups by surprise, spurring them to launch a public relations blitz highlighting their green bona fides, even if most of their work has been aimed at boosting their bottom lines.
Long a punching bag for consumer complaints and neighborhood protests over noise and poor air quality, the industry wants to avoid becoming a target on another front.
"People are looking across the Atlantic and seeing what is happening in Europe," said Nancy Young, the new vice president of environmental affairs at the Air Transport Association, U.S. carriers' main trade group. "We know that it's coming here. ... Aviation has lost the public square in this debate. We need to do a better job of letting people know that our environmental interests are directly aligned with our business interests."
Industry officials are quick to point out that commercial aviation contributes a very small percentage of the greenhouse gas and particle emissions that scientists blame for global warming. But they also acknowledge that aviation's impact could surge if the industry continues its worldwide growth spurt.
Boeing expects the number of commercial jetliners to nearly double, to 36,420, in the next 20 years. The Federal Aviation Administration expects 1.2 billion passengers a year to travel on U.S. carriers by 2020, up from 741 million last year.
By 2050, the industry is expected to contribute anywhere from 6 to 10 percent of the gases and particles tied to global warming, up from about 3 percent today, said Michael Prather, a professor at the University of California at Irvine and lead author of a 1999 report on aviation's role in global warming for the Intergovernmental Panel on Climate Change.
"It's a growth industry that lives off" jet fuel, Prather said.
Aviation's expansion has led to political problems for the industry in Europe, where there is increasing pressure to cut back on air travel, reduce airport expansion and increase taxes on tickets. Some religious leaders have suggested that flying on vacation is immoral.
In response, the European Union proposed rules that would require airlines serving domestic routes to enter into an emissions-trading scheme by 2011. Carriers flying to and from Europe, including U.S. airlines, would have to enter the system by the following year. The plan is based on one already in operation for other European industries that buy and sell credits to emit certain amounts of carbon dioxide.
The United States and other nations plan to vigorously fight the proposal at an international meeting of aviation authorities in Montreal in September. They say it would drive up costs for airlines and violate the principle of air-service deals brokered between governments. Moreover, they say, Europe doesn't have the right to force carriers to buy credits for carbon dioxide emitted in U.S. or international airspace, and they would rather set up a global framework for emissions trading than confront a hodgepodge of different regional systems.
"The emissions issue is real," said Marion Blakey, the FAA's administrator. "But we want to move forward on a global basis. To this point, the Europeans have shown no flexibility."
Some members of Congress are also skeptical of the European plan. House Transportation Committee Chairman James Oberstar, D-Minn., said he met in April with European leaders in Brussels and urged them to reconsider it. "It's an invasion of our sovereignty," he said.
Oberstar said he was concerned about aviation's effect on global warming and would hold hearings on emissions trading. An FAA funding bill under consideration in the House has several provisions dealing with greenhouse gas emissions, including the development of more fuel-efficient planes.
In the shadow of the global fight, U.S. airlines, international carriers and manufacturers have been pumping out press releases to highlight their efforts to be greener. They also do not hesitate to mention that they work in one of the few industries where reducing carbon dioxide emissions, the main culprit in climate change, is closely tied to their own economic well being. Fuel is the top expense for most carriers. Trade groups boast that last year U.S. airlines used about 1 billion fewer gallons of fuel than in 2000, but carried 12 percent more passengers.
"We make no bones that our saving fuel is in the company's best interest because we are saving dollars to the bottom line," American Airlines spokesman Tim Wagner said. "But the good news is that lies in a parallel direction with decreasing our environmental impact. ... Our corporate clients have been increasingly asking about global climate change."
American and Delta Air Lines jets, for example, often taxi using one engine to reduce fuel use, and the two carriers have promoted their efforts to add swept extensions to their planes' wings to reduce drag and boost efficiency. They are also pushing to incorporate better and more fuel-efficient navigation procedures into their operations.
American launched an effort to find ways to reduce the weight of planes, removing ovens, galleys and even potable water to make them lighter. And Delta has recently arranged for passengers to make donations to an environmental group to offset the carbon they emit on a flight. The group, the Conservation Fund, uses the money to plant trees.
In a recent speech, Giovanni Bisignani, the head of the International Air Transport Association, lauded the sector's 70 percent improvement in fuel efficiency since the dawn of the jet age. While admitting that "our carbon footprint is growing, and that is not politically acceptable," he set 2050 as a goal for having a "zero emissions" plane.
Bisignani said in an interview that he was hoping to get ahead of the debate because he was concerned that politicians would target airlines to boost "their green credentials."
"We are only a small part of an important problem," Bisignani said.