Emissions of short-haul vs long-haul

[milankl]

The following should be included in the assumptions of the manuscript:

The ICAO calculator

https://www.icao.int/environmental-protection/CarbonOffset/Pages/default.aspx

only takes into account the actually emitted CO2 per person per kilometer. Yes, if you take increased fuel consumption for the start and detour factors (which are bigger for shorter flights) into account you should end up with less fuel per km for longer flights. This effect becomes more or less negligible if the increased weight of the airplane due to more fuel is accounted for (Fig 1 in https://www.atmosfair.de/wp-content/uploads/atmosfair-flight-emissions-calculator-englisch-1.pdf). As far as I understand this in their report ICAO includes that with their freight load. What the ICAO however, doesn't take into account are the non-CO2 effects of aviation. There is some discussion here (and in the atmosfair report)

Section 8 in https://www.myclimate.org/fileadmin/user_upload/myclimate_-_home/01_Information/01_About_myclimate/09_Calculation_principles/Documents/myclimate-flight-calculator-documentation_EN.pdf

Which is based on the Jungbluth and Meili, 2018 report and others (atmosfair also references IPCC)

http://www.esu-services.ch/fileadmin/download/jungbluth-2018-IntJLCA-GWP-aviation-recommendations.pdf

In myclimate they simply multiply everything by 2 but atmosfair makes that actually height depended (as also recommended in that report as next level accuracy). As short-haul flights usually don't exceed 9km altitude this non-CO2 effect is larger for long-haul flights. This factor is then applied to the fuel consumption, which in turn is depended on the aircraft type. Neither myclimate nor ICAO nor any other calculator that I am aware of, except for atmosfair, allows to specify the aircraft type. I guess therefore that they all assume an average fuel consuming airplane. However, long-haul fleets seem to be on average newer and more efficient than short-haul (which also makes sense from an economic perspective of airlines). Interestingly, atmosfair raises an error if you try to calculate the carbon emissions for e.g. LHR-SIN with an Airbus A318. Correctly, as no A318 flies to Singapore. Atmosfair's calculation seems to include number of passengers and also passenger load factors of an airline (section 5 in their report). In total this seems to be a much more sophisticated way than in any other calculator, I therefore did a few atmosfair searches (e.g. London-Vienna, New York City-Vienna, Beijing-Vienna), and simplified them to 200gCO2e / km / person for short-haul and 250gCO2e/ km / person for long-haul (>1500km).

[milankl]

This is now included in the manuscript.