# Air travel and pollution **URL:** \ **Category:** Factual Questions\ **Created:** [September 2, 2010, 11:59am UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373 "2010-09-02T11:59:19Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![mr.jp](https://avatars.discourse-cdn.com/v4/letter/m/48db29/32.png) [@mr.jp](https://boards.straightdope.com/u/mr.jp)\ **Post date:** [September 2, 2010, 11:59am UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373/1 "2010-09-02T11:59:19Z")
My sister doesn’t want to take the airplane because it makes a lot of pollution. I’m wondering, how much does it actually cause, and what the negative value is. How much would she have to pay to offset the pollution she caused? ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [September 2, 2010, 12:12pm UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373/2 "2010-09-02T12:12:34Z")
What is her evidence? A nearly full B-747 delivers around 100 passenger-miles per gallon of fuel consumed. That’s quite a bit better than what’s typical for automobiles. If your sister travels by car, it’s likely the pollution she causes by burning fuel this way is greater (per passenger-mile) than what she’ll be responsible for if she flies. ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [September 2, 2010, 12:24pm UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373/3 "2010-09-02T12:24:31Z")
Whether she flies or not, the plane’s still going. ---
**Author:** ![qpw3141](https://avatars.discourse-cdn.com/v4/letter/q/6bbea6/32.png) [@qpw3141](https://boards.straightdope.com/u/qpw3141)\ **Post date:** [September 2, 2010, 12:29pm UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373/4 "2010-09-02T12:29:13Z")
> [@Xema](#): > > What is her evidence? > > A nearly full B-747 delivers around 100 passenger-miles per gallon of fuel consumed. That’s quite a bit better than what’s typical for automobiles. Not nearly fully loaded ones. Of course, a very small fraction of cars habitually travel nearly fully loaded. ---
**Author:** ![Baracus](https://avatars.discourse-cdn.com/v4/letter/b/2bfe46/32.png) [@Baracus](https://boards.straightdope.com/u/Baracus)\ **Post date:** [September 2, 2010, 12:29pm UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373/5 "2010-09-02T12:29:21Z")
> [@Xema](#): > > A nearly full B-747 delivers around 100 passenger-miles per gallon of fuel consumed. That’s quite a bit better than what’s typical for automobiles. If your sister travels by car, it’s likely the pollution she causes by burning fuel this way is greater (per passenger-mile) than what she’ll be responsible for if she flies. If it is _just_ the sister, then that is probably true. For a family of four, in a mid-size sedan, then driving will likely be less pollution producing per person. More so when one considers a more typical 737 (~80 passenger-miles/gallon) for a domestic flight. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [September 2, 2010, 1:01pm UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373/6 "2010-09-02T13:01:30Z")
It will depend on her definition of “pollution”. If CO2 is the concern, then as other posters have pointed out, aircraft aren’t that bad, in terms of CO2 emitted per passenger-mile. If other emissions (NOx, CO, UHC’s) are the concern, it’s very likely that commercial aircraft are putting out much more of those pollutants per passenger-mile than cars. Jet engines have been cleaned up considerably over the decades, but they burn at non-stoichiometric A/F ratios (which pretty much guarantees either high UHC’s/CO, high NOx, or both), and there’s no catalytic aftertreatment of the exhaust stream. Modern cars are held to _ridiculously_ tight standards with regard to these pollutants, so even when you consider the high passenger load of a commercial jet, it’s likely the per-person emissions are far higher. ---
**Author:** ![Giles](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/giles/32/60_2.png) [@Giles](https://boards.straightdope.com/u/Giles)\ **Post date:** [September 2, 2010, 1:36pm UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373/7 "2010-09-02T13:36:47Z")
You can only answer the question if you know what the alternatives are. One alternative is not to travel at all, of course, but if you do travel, how could you travel apart from by air? Bus and train should be less polluting, especially electric trains; car is probably more polluting; and ship is probably more polluting as well. (For ships you have to factor in that the trip will take several days, so you need cabins, dining rooms, kitchens, etc., all of which need fuel to transport them.) ---
**Author:** ![mr.jp](https://avatars.discourse-cdn.com/v4/letter/m/48db29/32.png) [@mr.jp](https://boards.straightdope.com/u/mr.jp)\ **Post date:** [September 2, 2010, 2:10pm UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373/8 "2010-09-02T14:10:20Z")
Aren’t there other alternatives. You can pay someone to not pollute as much, or grow a tree or something. I think the pollution must have an equivalent price somehow. ---
**Author:** ![Omar\_Little](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/omar_little/32/269_2.png) [@Omar\_Little](https://boards.straightdope.com/u/Omar_Little)\ **Post date:** [September 2, 2010, 2:58pm UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373/9 "2010-09-02T14:58:38Z")
Just let her stay home. Who would want someone like that chatting you up throughout your entire vacation. ---
**Author:** ![GiantRat](https://avatars.discourse-cdn.com/v4/letter/g/e47c2d/32.png) [@GiantRat](https://boards.straightdope.com/u/GiantRat)\ **Post date:** [September 2, 2010, 3:01pm UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373/10 "2010-09-02T15:01:18Z")
She can borrow a skateboard from the kid next door. The differential in time spent on the road (stopping for food, hotels, etc) goes a long way in offsetting. Plus, there’s value in conserving personal time so that she can actually enjoy the vacation/accomplish her work/whatever. ---
**Author:** ![JoelUpchurch](https://avatars.discourse-cdn.com/v4/letter/j/f05b48/32.png) [@JoelUpchurch](https://boards.straightdope.com/u/JoelUpchurch)\ **Post date:** [September 2, 2010, 3:12pm UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373/11 "2010-09-02T15:12:13Z")
The general rule of thumb is that flying in a scheduled airliner is about half the energy usage of driving by yourself, but Leaffan makes an important point. The incremental energy use when you fly is very small compared to a car trip. This applies to mass transit in general. A lot of mass transit system end up using more energy than driving, because they are lightly loaded most of the time, but mass transit should be used when it is available because the incremental energy per passenger is so small. Air Travel is mostly red herring. So little of our GHG emissions come from air travel that even if we totally banned air travel it wouldn’t make a dent in the problem. [http://depletedcranium.com/greenpeace-proposal-a-return-to-airline-glory-days-but-not-for-you/](http://depletedcranium.com/greenpeace-proposal-a-return-to-airline-glory-days-but-not-for-you/) ---
**Author:** ![NOLA\_Cajun](https://avatars.discourse-cdn.com/v4/letter/n/ea666f/32.png) [@NOLA\_Cajun](https://boards.straightdope.com/u/NOLA_Cajun)\ **Post date:** [September 3, 2010, 4:09am UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373/12 "2010-09-03T04:09:35Z")
I wonder how someone so concerned about pollution even knows about air travel since she obviously lives in a cave and is a hunter/gatherer and causes minimal pollution in her everyday life. What do those people use for tampons and toilet paper? Bark? Leaves? I’m of the opinion that the earth is pretty good at replenishing itself and even if it all does go to hell it will be well after I’m gone. So screw it. Let’s trash this place!! ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [September 3, 2010, 5:34pm UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373/13 "2010-09-03T17:34:50Z")
> [@mr.jp](#): > > I’m wondering, how much does it actually cause, and what the negative value is. Usually, enviromental organisations are concerned not only about the total amount of CO2 released, but also the fact that airplanes fly very high in the atmosphere, where the air is very thin, and conditions are different from the ground. Thus the scientists are concerned (though there is still not enough research to definitly confirm it because that takes decades) that the effect of one kg of CO2 released in the upper atmosphere is much worse than one kg of CO2 released at ground level. The usual recommendation is to take a train instead. The best option is if the train is powered by electricity generated regenerativly, = green (solar, wind, geothermal, water etc.) Or a solar-powered car/ electric car, again, depending on how the electricity was produced. Over here (Europe), there’s no real reason to use an airplane technically, because a train will get you there just as well. So if you aren’t crossing an ocean, take a train. (I know it will take longer, so business people have a reason. And traveling one hour to Yugoslavia instead of 12 hours can be an advantage if your health is not good. But for normal people, a longer travel time should be worth the benefit for the enviroment). > [@](#): > > How much would she have to pay to offset the pollution she caused? [Atmosfair](https://www.atmosfair.de/en/emissions-calculator/rechner/?no_cache=1)is generally highly regarded and meets the gold standard for CO2 compensation. I know that in the US, there is concern about shady organsiations ripping people off; but here, the enviromental groups watch them closely and other orgs. check them out. The [gold standard](http://www.cdmgoldstandard.org/) means that they not only plant trees for compensation of the released CO2, they also activly try to decrease future CO2 release with further measures, like sponsoring renewable energy projects in other countries. If she puts in her journey details into the calculator, the amount of CO2 released and the necessary cost for compensation should pop up. ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [September 3, 2010, 5:42pm UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373/14 "2010-09-03T17:42:13Z")
> [@From the atmosfair website](#): > > What impacts do the exhausts of aircraft engines have on the atmosphere, and especially in high altitudes? > > This question has been well answered by science by now. The greatest contribution to global warming stem from the following emissions and effects: > > The CO2 itself, as direct by-product of the combustion, the formation of cirrostratus clouds and / or contrails (linear clouds), the formation of the greenhousgas ozone in a sensitive atmospheric layer as well as the cooling effect of methane decomposition. We have data on the effect of contrails because during the days right after 9/11, when all air traffic was banned, a doctorate student in LA compared the weather measurements, esp. temperature, with the weeks immediatly before and after, and with the previous years, and found a difference of IIRC about 2 to 3 degrees C (which is an awful lot in metereology!). ---
**Author:** ![JoelUpchurch](https://avatars.discourse-cdn.com/v4/letter/j/f05b48/32.png) [@JoelUpchurch](https://boards.straightdope.com/u/JoelUpchurch)\ **Post date:** [September 3, 2010, 7:02pm UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373/15 "2010-09-03T19:02:35Z")
> [@constanze](#): > > > [@From the atmosfair website](#): > > > > What impacts do the exhausts of aircraft engines have on the atmosphere, and especially in high altitudes? > > > > This question has been well answered by science by now. The greatest contribution to global warming stem from the following emissions and effects: > > > > The CO2 itself, as direct by-product of the combustion, the formation of cirrostratus clouds and / or contrails (linear clouds), the formation of the greenhousgas ozone in a sensitive atmospheric layer as well as the cooling effect of methane decomposition. > > We have data on the effect of contrails because during the days right after 9/11, when all air traffic was banned, a doctorate student in LA compared the weather measurements, esp. temperature, with the weeks immediatly before and after, and with the previous years, and found a difference of IIRC about 2 to 3 degrees C (which is an awful lot in metereology!). Without the contrails the days were actually **hotter** and the nights were cooler. The contrails actually tend to moderate temperature swings. [http://www.pbs.org/wgbh/nova/sun/contrail.html](http://www.pbs.org/wgbh/nova/sun/contrail.html) > [@](#): > > Another study that took advantage of the grounding gave striking evidence of what contrails can do. David Travis of the University of Wisconsin-Whitewater and two colleagues measured the difference, over those three contrail-free days, between the highest daytime temperature and the lowest nighttime temperature across the continental U.S. They compared those data with the average range in day-night temperatures for the period 1971-2000, again across the contiguous 48 states. Travis’s team discovered that from roughly midday September 11 to midday September 14, the days had become warmer and the nights cooler, with the overall range greater by about two degrees Fahrenheit. ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [September 3, 2010, 7:23pm UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373/16 "2010-09-03T19:23:34Z")
Yes, the temps were higher. However, this still means that they are \*\* influencing\*\* the weather, and in a large amount - relative to their size - and the scientists have no idea of whether this influence is good or bad long-term, so it’s safer to reduce the influence as much as possible. ---
**Author:** ![mr.jp](https://avatars.discourse-cdn.com/v4/letter/m/48db29/32.png) [@mr.jp](https://boards.straightdope.com/u/mr.jp)\ **Post date:** [September 5, 2010, 11:32am UTC](https://boards.straightdope.com/t/air-travel-and-pollution/552373/17 "2010-09-05T11:32:19Z")
> [@mr.jp](#): > > > [@](#): > > > > How much would she have to pay to offset the pollution she caused? > > [Atmosfair](https://www.atmosfair.de/en/emissions-calculator/rechner/?no_cache=1)is generally highly regarded and meets the gold standard for CO2 compensation. I know that in the US, there is concern about shady organsiations ripping people off; but here, the enviromental groups watch them closely and other orgs. check them out. > The [gold standard](http://www.cdmgoldstandard.org/) means that they not only plant trees for compensation of the released CO2, they also activly try to decrease future CO2 release with further measures, like sponsoring renewable energy projects in other countries. > If she puts in her journey details into the calculator, the amount of CO2 released and the necessary cost for compensation should pop up. This was exactly what I was looking for! Thx.