Two things that are out of scope for this article: Emission altitude may change how certain emissions affect the environment and specifically the climate: &quot;Emissions weighting factor (EWFs) i.e., the factor by which aviation CO2 emissions should be multiplied to get the CO2-equivalent emissions for annual fleet average conditions is in the range 1.3–2.9.&quot;[0]<p>The other thing is that apart from the emissions per mile, you tend to travel more miles when you use a plane -- a magnitude more. Regardless of whether you take a car, a train or a plane, motorized mobility is only sustainable up to a point, and planes make it very easy to go (fly) beyond that point.<p>[0] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Energy_efficiency_in_transportation" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Energy_efficiency_in_transport...</a>