Jet pollution: drawing a line in the sky

Jet pollution: drawing a line in the sky: "Little is known about the global climate effects of airliner exhaust. Although jets create far less greenhouse gas than power plants or automobiles, they have an outsize impact because of where they spew it - the delicate upper troposphere and lower stratosphere, five to seven miles up from Earth's surface. And an expected boom in airline travel in coming years is likely to swamp any efficiency gains from the next generation of airliners, such as the just unveiled Airbus A380.

"The result: growing scientific concern that jets may be turning the skies into a hazier, heat-trapping place."