U.S. airlines under pressure to fly greener

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.