4 ms·

No, it does matter, we should use Warming Equivalent. "Warming equivalent" is the correct metric. Warming equivalents are typically given in Tons CO2 equivalen

No, it does matter, we should use Warming Equivalent. "Warming equivalent" is the correct metric. Warming equivalents are typically given in Tons CO2 equivalent. It's a way of converting methane and NO2 and other more powerful greenhouse gases to their CO2 equivalent. It's the standard metric anytime we're examining the climate impacts of actions. In the case of gasoline powered cars, I believe they just put out CO2, the other components are pretty negligible. So you can directly compare the warming equivalent of planes to the pure CO2 of cars, it's a reasonable comparison. It's worth double checking that last thing, it's been a minute since I looked at the numbers, but I'm about 85% sure of it.

deleted 7y ago
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mehrdadn 7y ago
Interesting... I just learned N2O is 300x worse than CO2. I don't know how to make a better comparison then. Some numbers I can find: "Aircraft engine emissions are roughly composed of about 70 percent CO2, a little less than 30 percent H2O, and less than 1 percent each of NOx, CO, SOx, VOC, particulates, and other trace components including HAPs." [1] For gasoline the ratio seems to be 51% CO2, 47% H2O, and 0.9% nitrogen oxides, and 1.3% other stuff (excludes nitrogen). [2] Water vapor isn't considered to be relevant when calculating CO2 equivalents so we can ignore that. [3] But I'm not sure how much the difference in NOx contribution is... given ground level emissions aren't the same as high-altitude and such. On the face of it it seems unlikely to me that the non-CO2 components would tip things in the other direction, but I'd definitely welcome better numbers... [1] https://www.faa.gov/regulations_policies/policy_guidance/envir_policy/media/aeprimer.pdf https://www.faa.gov/regulations_policies/policy_guidance/env... [2] https://en.wikipedia.org/wiki/Exhaust_gas#Spark-ignition_and_Diesel_engines https://en.wikipedia.org/wiki/Exhaust_gas#Spark-ignition_and... [3] https://climatechangeconnection.org/emissions/co2-equivalents/ https://climatechangeconnection.org/emissions/co2-equivalent...

deleted 7y ago

[deleted]

mehrdadn 7y ago

Interesting... I just learned N2O is 300x worse than CO2. I don't know how to make a better comparison then. Some numbers I can find: "Aircraft engine emissions are roughly composed of about 70 percent CO2, a little less than 30 percent H2O, and less than 1 percent each of NOx, CO, SOx, VOC, particulates, and other trace components including HAPs." [1] For gasoline the ratio seems to be 51% CO2, 47% H2O, and 0.9% nitrogen oxides, and 1.3% other stuff (excludes nitrogen). [2] Water vapor isn't considered to be relevant when calculating CO2 equivalents so we can ignore that. [3] But I'm not sure how much the difference in NOx contribution is... given ground level emissions aren't the same as high-altitude and such. On the face of it it seems unlikely to me that the non-CO2 components would tip things in the other direction, but I'd definitely welcome better numbers... [1] https://www.faa.gov/regulations_policies/policy_guidance/envir_policy/media/aeprimer.pdf https://www.faa.gov/regulations_policies/policy_guidance/env... [2] https://en.wikipedia.org/wiki/Exhaust_gas#Spark-ignition_and_Diesel_engines https://en.wikipedia.org/wiki/Exhaust_gas#Spark-ignition_and... [3] https://climatechangeconnection.org/emissions/co2-equivalents/ https://climatechangeconnection.org/emissions/co2-equivalent...