A couple of good articles in The Economist about aircraft greenhouse gas emissions. I have never understood why Greens don't more of an emphasis on decreasing aircraft travel. I guess in a way it seems unimportant:
In some ways, the airlines are an odd target for greens. They produce only around 3% of the world's man-made carbon emissions. Surface transport, by contrast, produces 22%. Europe's merchant ships spew out around a third more carbon than aircraft do, and nobody is going after them.But then you read this:
Within transport, aviation accounts for about 13% of co2 emissions. Its contribution to total man-made emissions worldwide is said to be around 3%.
One reason is that high-altitude emissions are probably disproportionately damaging to the environment. The nitrogen oxides from jet-engine exhausts lead to the formation of ozone, another greenhouse gas. Contrails are also suspected of enhancing the formation of cirrus clouds, which some scientists think adds to the global warming effect. The IPCC estimated that the overall impact on global warming of aircraft could be between two and four times that of their CO2 emissions alone, though there is no scientific consensus about the size of this multiplier.So, airplane travel has 2 to 4 times the impact on global warming as their CO2 emissions alone, and the growth in air travel is expected to offset all the reductions in carbon emissions that Britain is undertaking. Now it seems important. As they sum up eloquently:
Friends of the Earth commissioned a study from the Tyndall Centre for Climate Change Research to work out what growth of 6.4% a year (its average through the 1990s) would mean for Britain over the next 40-50 years. It concluded that the total CO2 discharges from air-traffic would soon offset all the reductions in carbon emissions scheduled under British government policies to comply with Kyoto. The European Commission (presumably neutral on such matters) accepts that, by 2012, the growth in aviation would offset more than a quarter of the reductions that its richer members hoped for.
What this means is that the eco-conscious European consumer who jets off for a series of weekend breaks is destroying his day-to-day carbon parsimony. You can buy a hybrid car, switch to low-energy light bulbs in your house and eat locally grown organic food. But the dozen daily decisions on which you base your husbandry are trivial compared with the handful of yearly choices about that holiday or this business trip.I would love to see a "vacation locally" green campaign that talks about the CO2 emissions that occur from long flights. There seems to be a lot of anti-Hummer Greens but not many anti-frequent flyers Greens, and I just don't get this (as I wrote about before). It is like they believe emissions from flying don't count.
Depending on your assumptions, traveling by aircraft isn't even the most efficient way to travel as this graph shows. And that doesn't even take into account that people typically travel much farther when they travel by plane.
To put the impact of flying in perspective lets compare a family trip to Japan with a Hummer Indy 500.
A round trip flight from LA to Tokyo (or London) is a little more than 10,000 miles round trip. Taking a family of four on a vacation to Tokyo uses approximately 800 gallons of fuel and emits 8 tons of CO2 (using Climate Care for the estimate). If you use the fact that airline emissions have 2 times the impact on global warming as those emitted by cars (and this is on the low end of the estimate), this is the same as 16 tons of CO2 emitted by cars.
If you had 32 Hummers (at 10 mpg) run the Indianapolis 500 (for a total of 16,000 miles driven), they would emit 16 tons of CO2.
Most Greens would be aghast at the idea of a Hummer Indianapolis 500, but would have only nice things to say when told of a family going on a Japanese vacation. And yet their impact on global warming is about the same.
Now I understand that if you do want to go to Tokyo, there is really no other way to do it but fly. On the other hand, if you are driving a Hummer you can substitute with a more efficient vehicle. But, you do have a choice on where you take your vacations and if you are serious about reducing fossil fuel usage then the distance of your destination should be taken into account. Substituting a family trip to Disneyland rather than a trip to Tokyo saves 8 tons of CO2 from being emitted. Changing from an SUV that gets 20 mpg to a Prius that gets 40 mpg, only saves 3 tons of CO2 a year (assuming 12,000 miles a year). The location of your vacation destinations is likely the most important environmental decisions you make all year.