Related: I was surprised to learn recently that short-distance trips by plane actually have lower CO2-emissions than long-distance ones, because the plane does not need to carry so much fuel just for later use.
https://www.yaleclimateconnections.org/2015/09/evolving-clim... says "Longer flights are more efficient overall, as cruising requires less fuel."
https://www.theguardian.com/environment/2010/apr/06/aviation... also states "short flights tend to be more harmful to the climate per mile travelled than long-haul flights are (because they have more empty seats, and because taking off and landing burns more fuel than cruising)".
[0] https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft#Fligh...
Interesting tidbit (from the same): Very long non-stop passenger flights suffer from the weight penalty of the extra fuel required, which means limiting the number of available seats to compensate. For such flights, the critical fiscal factor is the quantity of fuel burnt per seat-nautical mile. For these reasons the world's longest commercial flights were cancelled c. 2013. An example is Singapore Airlines' former New York to Singapore flight, which could carry only 100 passengers (all business class) on the 10,300-mile (16,600 km) flight. According to an industry analyst, "It [was] pretty much a fuel tanker in the air."
https://en.wikipedia.org/wiki/Singapore_Airlines_Flights_21_...
Of course, it comes with its share of drawbacks as well. But if it was to allow lighter planes, and less fuel expenses/burnt, it could well be worth it.