Aviation and the environment are on a collision course. The number of airline flights worldwide is growing and expected to skyrocket over the coming decades. Aircraft emissions pollute the air and threaten by 2050 to become one of the largest contributors to global warming, British scientists have concluded.
Much remains unknown about climate change and the role aviation plays, though climate scientists express particular concern about jet emissions in the upper atmosphere, where the warming effect from some pollutants is amplified.
Now, aviation is believed to be less a factor in the Earth's warming than power plants or vehicular traffic. But its emissions are considerable. On a New York-to-Denver flight, a commercial jet would generate 840 to 1,660 pounds of carbon dioxide per passenger. That's about what a typical driver generates with an SUV in a month.
With the projected explosion in worldwide travel, air pollution from aviation is a growing concern among scientists, and it's drawing increased scrutiny from governments, particularly in Europe.
"It's an issue that has to be addressed," says Brenda Ekwurzel, a climate scientist for the Union of Concerned Scientists, an environmental advocacy group.
David Travis, a climate science professor at the University of Wisconsin-Whitewater, says aircraft emissions "are currently one of the fastest-growing contributors to global warming."
The European Union is considering strict controls on aircraft emissions, an action strongly opposed by the White House because of its potential effect on U.S. airlines.
Some members of the British Parliament favor limiting the growth rate in the number of air passengers to the rate at which aviation improves its fuel efficiency. Last month, a local government council rejected a plan to increase flights at London's Stansted airport because of concerns about the environment and global warming.
In the USA, a panel of scientists brought together by NASA and the Federal Aviation Administration agreed in August that the effects of aircraft emissions on the climate "may be the most serious long-term environmental issue facing the aviation industry."
The FAA projects that the number of U.S. airline passengers will nearly double from 739 million last year to 1.4 billion in 2025. Air traffic controllers are expected to handle 95 million flights by all types of aircraft in 2025, compared with 63 million last year. Worldwide, a growing middle class with the means to travel is spawning new airlines and big orders for new planes. China plans more than 40 new airports to accommodate the growth.
By 2050, emissions from planes are expected to become one of the largest contributors to global warming, according to the Royal Commission on Environmental Pollution, an independent group of scientists that advises the British government.
Although the USA is the largest emitter of carbon dioxide -- a pollutant that scientists believe is a major contributor to global warming -- the Bush administration refuses to ratify the Kyoto Protocol. That 1997 agreement is limiting emissions from such big polluters as power plants and automobiles in more than 160 countries. President Bush says the agreement would hurt the economy. He also says it's unfair because it exempts China, another major polluter.
Aviation emissions are not part of the Kyoto Protocol. Emissions from planes were considered a minor problem when the agreement was negotiated, but several scientific studies have since shown otherwise, says European Commission spokeswoman Barbara Helfferich.
In the USA, aircraft emission standards set by the Environmental Protection Agency mirror those of the International Civil Aviation Organization (ICAO), the group that sets worldwide standards. The FAA enforces the EPA's standards.
Clouds of ice formed in the trails of jet exhaust trap heat and prevent the earth from cooling.
Aviation is going green from ticketing to takeoff by modernizing equipment, reducing fuel consumption and exploring new technologies.
Aviation expert Mike Boyd said he thought high-profile announcements by airlines are akin to building a firebreak to show the industry is taking some action.