Christie Aschwanden decided to stay home for a year. Not because she doesn't like to travel, but because she doesn't like what travel does to the environment:
It's not that I ever thought flying was environmentally harmless, but I'd never appreciated the magnitude of its destructiveness. It seemed to me that traveling in a jumbo jet packed with passengers was sort of like riding a bus through the sky -- public transportation is good, right?
The numbers told me otherwise. A nonstop flight from San Francisco to New York puts you on the hook for 2.23 tons of carbon dioxide. Fly first class, and the extra space you occupy bumps you to 5.59 tons -- more than twice the 2.2 tons you'd emit driving a midrange car 7,500 miles. It's not just aviation's carbon emissions that make it so bad for the climate, it's also factors like vapor trails and ozone as well as where a jet's emissions occur -- in a sensitive part of the atmosphere where their effects become magnified. Scientists call this effect "radiative forcing" and calculations that don't include it can make flying seem deceptively benign. Don't be fooled: Every time you get on an airplane, you're helping to shove a Bangladeshi's home under water.
Yet despite the danger, flying rarely provokes the kind of environmental shame that driving a Hummer or running the washer and dryer with a single item might. It's hard to say exactly why, but I have a theory -- it's easy to act like an environmentalist when it means buying cool new stuff like reusable grocery bags, a high-efficiency washer, or a hybrid car. When doing the green thing requires actual sacrifice or a substantial change in lifestyle, well, that's where most of us draw the line.
Why does air travel get left out of the mix when we're talking about reducing our carbon footprint? One could argue, because cars matter more -- they're the largest single contributor to climate change in the transportation sector. Air travel accounts for about 10 percent of all carbon emissions in the U.S., versus 36 percent for passenger cars -- and some of that is air freight.
However, the majority of flight departures and air tonnage seem to be passenger travel, not freight. And although many car trips are hard to avoid, given 60 years of infrastructure development, a lot of the air travel is unnecessary -- and concentrated among the so-called one percent. Only abouthalf the country takes as much as one flight a year; I'm willing to bet that virtually every U.S. citizen gets in a passenger car at least once per annum. And while most of those car trips are the business of everyday life -- getting to work, procuring food, etc. -- most of those flights are either vacations, or elite workers flitting to conferences and business meetings.
Those trips are simultaneously less necessary and more carbon intensive; almosteight timesas many passenger miles are traveled by car as by plane, but passenger car travel only accounts for 3 to 4 times as much greenhouse gas emission. Moreover, while we may eventually wean cars off of gasoline, air travel will, I'm told, pretty much always require hydrocarbons; nothing else can contain so much energy in so little weight, which means they're the only way to get the plane off the ground. Air travel is not only bad for the environment now, but also will be bad for the environment 30 years from now.
So why, pray tell, do we spend so much time talking about suburban sprawl and sport utilities, and so little time talking about FedEx and European vacations?
The question answers itself, doesn't it? Giving up air travel and overnight delivery is much more personally costly for the public intellectuals who write about this stuff than giving up a big SUV. If you live in one of the five or six major cities that contain virtually everyone who writes about climate change, having a small car (or no car), is a pretty easy adjustment to imagine. On the other hand, try to imagine giving up far-flung vacations, conferences, etc. -- especially since travel to interesting locales is one of the hidden perks of not-very-well remunerated positions at universities, public policy groups, nongovernmental organizations, and yes, news organizations.
If we're going to get serious about greenhouse gasses, we need to get serious about air travel. Going to a distant conference should attract the kind of scorn among the chattering classes that is currently reserved for buying a Hummer.
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Megan McArdle at firstname.lastname@example.org