You are now free to pollute about the country

Air travel is the latest guilt trip for the environmentally conscious consumer. Here's how flying contributes to global warming and what is being done to cool the jets.

By Katharine Mieszkowski

Read more: Politics, News, Airlines, Global Warming, Katharine Mieszkowski

July 18, 2007 | This spring, meteorologist Robert Henson was thrilled to be one of the six finalists for the prestigious Royal Society Prize for Science Books for "The Rough Guide to Climate Change." There was only one problem: All finalists were required to appear at the awards ceremony. Henson lives in Boulder, Colo. The ceremony was in London.

The irony of jetting halfway around the globe and back -- merrily spewing the greenhouse gases that contribute to global warming -- to honor a book about the pressing dangers of the warming planet was not lost on the meteorologist. "I wanted to be there, and I had agreed I would be there by entering the contest," says Henson. "But I wanted to do it in the most greenhouse-friendly way that I could."

So Henson resolved to make the flight entirely during daylight hours, when greenhouse emissions from jets are reportedly less harmful. That meant flying from Denver to Washington, D.C., staying overnight in a hotel, and then catching another flight the next day to London.

Worry about air travel's contribution to global warming is taking off. In England, grass-roots activists have locked horns with the airline industry over its increasing number of flights and plans for airport expansion. One group, Plane Stupid, blocked a runway, delaying flights in Nottingham, and disrupted a meeting of airline executives by releasing a bunch of helium balloons with screeching alarms. One Plane Stupid protester went so far as to Super Glue herself to the door of the corporate offices of Lastminute.com, an online travel agency. Not to be outdone, in June Greenpeace activists dressed up as stewardesses, set up booths called "climate ticket exchanges" at four airports, including Heathrow, and handed out free train tickets to passengers willing to skip their short flights and go by rail instead. The goal: to stress train travel as a climate-friendly alternative to flying, especially for that short hop to Paris.

The climate clamor over flying doesn't stop with environmental activists. One British bishop denounced flying on a vacation as a "sin." Even publishers of travel books lament the climate impact of their wanderlust guides and are advising travelers to "fly less and stay longer." Mark Ellingham, founder of Rough Guides, and Tony Wheeler, founder of Lonely Planet, have decried the growth of what they call "binge flying," and urged air travelers to take to the skies less often. "In Europe, and especially Britain, we have become addicted to cheap flights, heading off to Rome for the day or Prague for the weekend," writes Ellingham in e-mail. "Many people buy these as casually as booking a restaurant. I consider this 'binge flying' and I don't think it's sustainable behavior."

How worried should air travelers be about contributing to global warming? Flying still makes up a very small percentage of greenhouse gas emissions. Globally, just 1.5 percent of greenhouse gas emissions caused by human activity each year come from air travel, according to Tim Herzog, a climate policy analyst for the World Resources Institute. In the U.S., that number's about 3.5 percent. Yet those numbers are projected to rise sharply, making air travel one of the fastest growing contributors to global warming, while the world is struggling to reduce emissions. Over the next 20 years, more than 27,000 new aircraft will take flight, and the number of air travelers will double to 9 billion during the same period, according to the Hodgkinson Group, an aviation consulting firm. Here in the United States in the next two decades, demand for air travel will grow 150 percent, according to the Department of Energy.

Some governments are stepping in to curb the rising tide of emissions. By 2011, airplanes traveling within the European Union will be subject to a carbon trading scheme. But debate about such regulations inspired the unrepentant boss of one low-cost airline, Ryanair, to pledge to increase his company's carbon emissions, saying if his customers are worried about the environment, he had some advice for them: "Sell your car and walk."

Hopping a commercial flight sure feels like an airborne form of carpooling, especially when the blowhard sitting next to you won't close his yapping trap for six hours. And, sure, fine, it's unquestionably better for the environment than owning a private jet, which one horrified activist compared to buying a whole coal-fired power plant to power a single mobile phone. Yet even on today's full flights with passengers crammed into small seats, flying packs a big climate punch. For a long trip, like a transatlantic flight on an average-size plane, each passenger is responsible for sending .39 pounds of CO2 per mile into the atmosphere, according to the World Resources Institute's Greenhouse Gas Protocol Initiative. By that measure, flying direct from Denver to London and back puts about 3,600 pounds of CO2 into the atmosphere, equivalent to driving a Toyota Prius hybrid 10,000 miles.

While most Americans still emit more by driving than flying, simply because they spend so many hours in the car, frequent fliers can spew a lot more emissions than daily commuters. Take the doting grandmother, recently profiled in the New York Times, who flies 500 miles a week, jetting from her home in Houston to Dallas and back to care for her grandkids, a tale the paper dubbed "The Incredible Flying Granny Nanny." A year of this high-flying childcare arrangement will pump almost 16,500 pounds of C02 into the atmosphere, more than the average driver of a four-wheel-drive Ford Ranger emits in a year.

It may be a short flight from Houston to Dallas, but shorter flights have a larger impact per mile than longer ones, since the takeoff and landing are the most fuel-hungry part of the journey. "These regional flights are not efficient because they don't have time to get up into the atmosphere and cruise, where jets are most efficient," says Luke Tonachel, a vehicles and fuels analyst for the Natural Resources Defense Council. That means the Incredible Flying Granny emits .63 pounds per mile every time she jumps on a jet to see the grandkids. She could reduce her emissions by hopping behind the wheel of a Honda Civic by herself and driving from Houston to Dallas and back.

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