Air Travel

LAST fall, when Democrats and Republicans seemed unable to agree on anything, one bill glided through Congress with broad bipartisan support and won a quick signature from President Obama: the European Union Emissions Trading Scheme Prohibition Act of 2011.

It is for me. And for people like Al Gore or Richard Branson who crisscross the world, often by private jet, proclaiming their devotion to the environment.

Though air travel emissions now account for only about 5 percent of warming, that fraction is projected to rise significantly, since the volume of air travel is increasing much faster than gains in flight fuel efficiency. (Also, emissions from most other sectors are falling.)

In an unsuccessful lawsuit before the European Court of Justice last year, United States airlines argued in part that the European Union had no right to tax emissions on trans-Atlantic flights because they went into international airspace.

He said that Qantas, the Australian airline, is going along with the European scheme, under which airlines must buy so-called carbon allowances if they exceed assigned annual emissions targets, which decrease year by year.

This year, the European Union is collecting the emission payments on flights within Europe as per the original schedule. That has made it harder for European carriers to compete in a cutthroat industry, said Thomas Kropp, a senior vice president at Lufthansa.

Ms. Hedegaard, the European Union commissioner, said that if the International Civil Aviation Organization fails to come up with a solid, market-based program in September, the European Union will begin collecting the emissions fees for all flights in and out of its airports. One way or another, prices seem bound to increase some, and perhaps that is fair. We spend more for LED light bulbs and hybrid vehicles in part because we care about the environment.

Elisabeth Rosenthal is a reporter on the environment and health for The New York Times.

A news analysis article last Sunday about the impact of air travel on global warming referred imprecisely to the environmental impact of one round-trip flight from New York to Europe or to San Francisco. It has a warming effect equivalent to 2 or 3 tons of carbon dioxide per person, but does not generate that much carbon dioxide per person. (The estimate also includes warming from other greenhouses gases.)

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