4 ms·

My quick google says it's 2.5% of carbon emissions (for both passengers and cargo). If we add a carbon tax, do you consider the prime benefit to be the reducti

My quick google says it's 2.5% of carbon emissions (for both passengers and cargo). If we add a carbon tax, do you consider the prime benefit to be the reduction in demand (if it means 20% less air travel, that's .5% total global carbon emissions reduction) Or do you feel like the prime benefit is to spur/incentivize more carbon neutral strategies (like electric aircraft?)? Or, do you feel like the primary benefit would be the "offsets" (like protecting trees, carbon capture technology, etc) I see a lot of talk about reducing carbon emissions, but it seems like there are a lot of things a "carbon tax" could change, and I feel like deciding on what one of those is the primary benefit is a harder problem than leveraging the tax in the first place.

edmundsauto 4y ago
Naive question: Are airliner emissions more harmful because they are further up in the atmosphere?
- vkou 4y ago
  Yes, they are, but not vastly. Air travel is still a small fraction of the average westerner's carbon footprint.
  - edmundsauto 4y ago
    But aren't some of the emissions (sulfur based ones) significantly more harmful than pure CO2 released, and (from what I remember about Nathan Myhrvold's work) much more impactful when released at 40k feet? Just wondering if measuring the CO2 volume is less relevant when talking about releasing sulfurs at altitude.
  - criddell 4y ago
    Is that because the average westerner doesn’t fly every year? How does it change if you only look at people who fly?
    - vkou 4y ago
      I'm talking about average, not median. Ground transportation and home energy use and industrial energy use all dwarf the average flight emissions.
      - criddell 4y ago
        I’m asking about individuals. I’ve flown a couple times this year. I’ve been airborne for about 20 hours. Are you saying my portion of the emissions from those flights is likely negligible compared to the emissions from owning a home and car?
        vkou 4y ago
        Yes, actually, if you commute by car, or if you don't live in a ~fully-green energy state. 20 hours of flight is ~10,000 flight miles. A 737 gets ~80 mpg per passenger seat. Takeoff is an extra ~20% in an average flight's fuel consumption.
- ch4s3 4y ago
  No they are not. Airliners fly in the lower stratosphere, the troposphere is what is primarily warming. The effects on ozone are another story. [edit] for anyone downvoting, I'm referencing this paper[1] in the Encyclopedia of Global Environmental Change from 2002, which says: > Increases of the concentration of small particles emitted from aircraft with similar residence times have also been measured near dense flight routes. CO2 on the other hand, has a lifetime of the order of 100 years and gets distributed essentially over the whole atmosphere. Therefore, the effects of CO2 emissions from aircraft are indistinguishable from the same quantity of CO2 emitted at the same time by any other source. It's consistent with older research as well, and I can't find anything newer that refutes the claim. [1] https://www.dlr.de/pa/en/Portaldata/33/Resources/dokumente/mitarbeiter/Schumann_Encyclopedia_Aircraft_Emissions_c415-_o.pdf https://www.dlr.de/pa/en/Portaldata/33/Resources/dokumente/m...
  - nkurz 4y ago
    I think your reasoning is correct for CO2, but the OP asked about "emissions" in general. For some of these, the dispersion is less, and thus the high altitude does make a difference. I've only skimmed it, but this seems to be a good paper describing the different effects: http://www.anjakollmuss.com/wp-content/uploads/2017/04/SEI_Air_Travel_Emissions_Paper2_June_09.pdf http://www.anjakollmuss.com/wp-content/uploads/2017/04/SEI_A... While agreeing that a multiplier is not strictly correct, they recommend applying multiplier "greater than 2" to properly account for the non-CO2 effects of air traffic on global warming: Though science-based reasoning discourages the use of a simple multiplier to account for non-CO2 effects, such a multiplier is desirable from a policy and climate protection point of view. We elaborate on a number of scientific and value-related issues and conclude that a multiplier of 2 or greater should be used for air travel emissions calculators to account for non-CO2 warming effects.
    - ch4s3 4y ago
      Yeah I understood the OP to mean c02 and added the caveat about other emissions. It seems pretty uncertain, especially as lower level stratospheric mixing seems poorly understood. But, my understanding extends only as far as having read 3 papers on the topic.
- dymk 4y ago
  From some googling, they lack catalytic converters, so the emissions they do put out are more harmful to the environment per-pound-produced than what comes out of a car's tailpipe.
xorcist 4y ago
Any type of reduction would be a huge deal. 0.5% net is more than most would dare to hope for. Remember that each and every year we release more carbon in the atmosphere than the year before. So far with only one exception, during the covid lockdowns, but now we're back again with an even bigger increase than before.

edmundsauto 4y ago

Naive question: Are airliner emissions more harmful because they are further up in the atmosphere?

vkou 4y ago
Yes, they are, but not vastly. Air travel is still a small fraction of the average westerner's carbon footprint.
- edmundsauto 4y ago
  But aren't some of the emissions (sulfur based ones) significantly more harmful than pure CO2 released, and (from what I remember about Nathan Myhrvold's work) much more impactful when released at 40k feet? Just wondering if measuring the CO2 volume is less relevant when talking about releasing sulfurs at altitude.
- criddell 4y ago
  Is that because the average westerner doesn’t fly every year? How does it change if you only look at people who fly?
  - vkou 4y ago
    I'm talking about average, not median. Ground transportation and home energy use and industrial energy use all dwarf the average flight emissions.
    - criddell 4y ago
      I’m asking about individuals. I’ve flown a couple times this year. I’ve been airborne for about 20 hours. Are you saying my portion of the emissions from those flights is likely negligible compared to the emissions from owning a home and car?
      - vkou 4y ago
        Yes, actually, if you commute by car, or if you don't live in a ~fully-green energy state. 20 hours of flight is ~10,000 flight miles. A 737 gets ~80 mpg per passenger seat. Takeoff is an extra ~20% in an average flight's fuel consumption.
ch4s3 4y ago
No they are not. Airliners fly in the lower stratosphere, the troposphere is what is primarily warming. The effects on ozone are another story. [edit] for anyone downvoting, I'm referencing this paper[1] in the Encyclopedia of Global Environmental Change from 2002, which says: > Increases of the concentration of small particles emitted from aircraft with similar residence times have also been measured near dense flight routes. CO2 on the other hand, has a lifetime of the order of 100 years and gets distributed essentially over the whole atmosphere. Therefore, the effects of CO2 emissions from aircraft are indistinguishable from the same quantity of CO2 emitted at the same time by any other source. It's consistent with older research as well, and I can't find anything newer that refutes the claim. [1] https://www.dlr.de/pa/en/Portaldata/33/Resources/dokumente/mitarbeiter/Schumann_Encyclopedia_Aircraft_Emissions_c415-_o.pdf https://www.dlr.de/pa/en/Portaldata/33/Resources/dokumente/m...
- nkurz 4y ago
  I think your reasoning is correct for CO2, but the OP asked about "emissions" in general. For some of these, the dispersion is less, and thus the high altitude does make a difference. I've only skimmed it, but this seems to be a good paper describing the different effects: http://www.anjakollmuss.com/wp-content/uploads/2017/04/SEI_Air_Travel_Emissions_Paper2_June_09.pdf http://www.anjakollmuss.com/wp-content/uploads/2017/04/SEI_A... While agreeing that a multiplier is not strictly correct, they recommend applying multiplier "greater than 2" to properly account for the non-CO2 effects of air traffic on global warming: Though science-based reasoning discourages the use of a simple multiplier to account for non-CO2 effects, such a multiplier is desirable from a policy and climate protection point of view. We elaborate on a number of scientific and value-related issues and conclude that a multiplier of 2 or greater should be used for air travel emissions calculators to account for non-CO2 warming effects.
  - ch4s3 4y ago
    Yeah I understood the OP to mean c02 and added the caveat about other emissions. It seems pretty uncertain, especially as lower level stratospheric mixing seems poorly understood. But, my understanding extends only as far as having read 3 papers on the topic.
dymk 4y ago
From some googling, they lack catalytic converters, so the emissions they do put out are more harmful to the environment per-pound-produced than what comes out of a car's tailpipe.

xorcist 4y ago

Any type of reduction would be a huge deal. 0.5% net is more than most would dare to hope for. Remember that each and every year we release more carbon in the atmosphere than the year before. So far with only one exception, during the covid lockdowns, but now we're back again with an even bigger increase than before.