Greenhouse gas emissions from domestic commercial aviation have fallen 13 percent between 2000 and 2006, according to recently released figures from the Environmental Protection Agency. I blogged about a USA Today article on this report last week, and I finally tracked down the original, cleverly obscured on the EPA website. (The aviation-relevant sections are here and here.) The pattern of greenhouse gas emissions from aviation mirrors consumption of fuel. Carbon dioxide is by far the most common greenhouse gas to be emitted, although relatively small amounts of methane are emitted , especially during takeoff and landing, along with nitrous oxides. (Newer engines have to comply with EPA rules limiting nitrous oxide emissions.)
The relationship between jet fuel consumption and all aviation emissions (including general aviation and military flights) is even more closely mirrored.
But did emissions fall just because of the 2000-2001 recession and September 11, both of which did a number on the airline industry? That is not clear. As the chart below shows, with the exception of a post-9/11 slump, passenger totals grew even as emissions declined:
This means that U.S. airlines have done a better job of transporting passengers on less fuel. This includes harmonizing schedules, increasing load factors, switching to more fuel efficient aircraft and engines, and generally undertaking fuel-saving measures. (Alaska Airlines, for example, bought lighter aluminum beverage carts to replace their steel ones.) The FAA also takes some credit for the drop in emissions, including the introduction of Reduced Vertical Separation Minimum and Continuous Descent Arrival, and it promises even greater gains with the NextGen program to transform air traffic control and allow planes to fly more direct routes.
It also shows that increasing the cost of fuel will force airlines to do with less of it. The several-times-over run-up in oil prices since 2000 has functioned like a de facto carbon tax, albeit one that does not generate government revenue or necessarily lead to investments in alternative energy or climate change mitigation.
I’m not convinced that we are close to “carbon-neutral” growth, as FAA associate administrator Daniel Elwell said recently. He is attributing a lot of the projected efficiency gains to NextGen, which is way behind schedule and way over budget. But all the same, I’m pleased and impressed with the U.S. performance in reducing its aviation-related greenhouse gas emissions.
From here, I turn it over to commentators who are better-versed in climate change and environmental policy.