Air Travel II: Learning to Fly

by Ben Carmichael  |  April 28, 2008  |  More By Ben Carmichael

Sometime during the afternoon of December 17, 1903, the Wright brothers flew their airship -- by modern standards a matchbox of spruce and muslin -- 120, 175 and 200 feet. The distances seem paltry in comparison to the architecture of modern aircraft, where wingspans regularly extend over 220 feet. But this would be to forget that the Wright brothers' contribution was not flight, but the control of it.

By the time the Wright brothers made their flight in 1903, the record of men who had taken to, and fallen from the skies in varying degrees of control, had established heavier-than-air flight as a distinct possibility. Otto Lilienthal made the first successful gliding attempts from the artificial hills he built around Berlin, earning him the name "Glider King." Before him was George Cayley, the father of aerodynamics, and before him, Da Vinci, whose sketches of hang gliders and helicopters varied between the impractical and the inspired.

120, 175 and 200 -- small distances each, to read them anachronistically. But here, the anachronism may actually yield something, because it asks the question: how do we measure the impact of current air travel? Or, asked slightly differently, can we measure its impact at all?

For the carbon conscious, measuring one's carbon footprint has become an obsession that has begun to exert significant impact on the consumer market. The airline industry is particularly vulnerable to such concerns. With air travel poised to double by 2050, and with people's carbon consciousness at a peak, people are flocking to websites that measure the carbon emissions of their travel.

Last year, Americans spent $54 million on carbon offset programs. Companies such as Terrapass and co2balance.com are responding to consumer demand by offering customized calculations of carbon emissions and offsets, while conservation groups like The Nature Conservancy and The Conservation Fund offer carbon calculators for such activities as car and train travel, households and food.

A quick, informal survey across these carbon calculators reveals an obvious conclusion: they all make different recommendations. Take, for instance, the difference between the results I received by calculating an air ticket between Washington, DC and London, UK: 1.4, 1.6, 2.1 tonnes and 2.2 tons. This would cost me anywhere from $12 to £40.

The difference between these numbers reveals the simple truth that we don't yet understand how to put a price on carbon. And that the barrier to this understanding is the great complexity of the issues involved: between global economies and global ecologies are systems that have, for centuries, valued different things. The process of aligning them will take more time than an online search. But moreover, between each flight there is also a great deal of difference that prevents a simple, standard calculation.

While some online calculations do make distinctions between long and short term air travel, estimates range from as low as 0.1 pounds of CO2 per passenger mile traveled up to 1 pound. Not only is our understanding of this issue is still incomplete, but the law of averages just doesn't apply to air travel.

Every flight is going to require a different plane, and every plane a different amount of jet fuel to travel a different distance, depending upon factors like age, cargo, passengers, air traffic and wind speed, to name only a few.

I emailed Chris Calwell, who worked with NRDC's energy program from 1988 to 95, and now is Vice President and Director of Policy and Research at Ecos, a Durango based energy consultancy, to ask him about air travel. He had something interesting to say:

"What makes the calculation even more nerve-racking is that any individual passenger only causes a slight increase in marginal emissions (due to their weight). The plane would have flown anyway, so is it fair to impute 1% of a plane's total emissions for a flight to 1 person if the plane has 100 people aboard? Each incremental passenger added to the flight up to its capacity is probably actually reducing emissions per passenger mile, even if they're slightly increasing total emissions."

All this creates a background of information against which the language of broad description does more to capture the impact of flying than specific figures. Take, for instance, a description by Tufts Climate Initiative:

"The average American is responsible for the emissions of about 20 tons of CO2 annually, the average European or Japanese for about half that. If you fly to Europe and back from the US, you'll add about 3-4 tons to your (already large) carbon footprint. With one flight you will have caused more emissions than 20 Bangladeshi will cause in a whole year. Unfortunately they are the ones who will lose their homes and livelihood once sea level rise inundates their low lying country."

The history of flight is a record of aspiration –- of men buoyed by a mix of dedication, and inspiration that, to us, can read as folly. Otto Lilienthal, for his part, devoted his life to flying. It was everything to him. “To invent an airplane is nothing,” he is quoted as saying. “To build one is something. But to fly is everything.” Samuel Pierpont Langley, another aviation pioneer, gave up flying after two near fatal crashes. Orville Wright, for his part, was convinced that the exhausting struggle to gain a patent for their discovery lead to the early death of his brother Wilbur.

As we consider the impacts of aviation on climate change, we might remember the truism that what goes up, goes up, before coming down. On August 9, 1896, Lilienthal fell from a glider at a height of 56 feet and broke his spine. Before dying the next day, he said, “Small sacrifices must be made!”

Myth or not, Lilienthal seemed to know the cost of his sacrifice. We do not. For him it was a life. What will it be for us? At what cost will we continue to fly?

(Note: This is the second in a series of posts about air travel. Click here for the first.)