Re: Next steps towards a net zero IETF

[Andrew McConachie <[e-mail]>]

On 25 Mar 2023, at 16:37, Christian Huitema wrote:

> On 3/25/2023 5:36 AM, Julian Reschke wrote:
>> On 25.03.2023 11:48, Andrew McConachie wrote:
>>> ...
>>> Trains and planes are fundamentally different in this regard, 
>>> because
>>> planes calculate their weight at takeoff and only take as much fuel 
>>> as
>>> they need. The amount of CO2 produced by a passenger plane is 
>>> directly
>>> proportional to how many passengers it’s carrying.
>>> ...
>>
>> So a passenger plane not carrying any passengers is not producing any 
>> CO2?
>
> I think Andrew erred when he said "directly proportional". As in many 
> things, you can probably separate fixed costs and variable costs. 
> There is a fixed cost to carrying the whole weight of the empty plane 
> and the crew through the sky. There is also a variable cost based on 
> the load of the plane, which for a passenger plane means the weight of 
> passengers and their luggage. So yes, an additional passenger directly 
> increases the fuel consumption of the plane -- but less so than if too 
> few passengers lead the airline to fly fewer planes. And the "fewer 
> plane" effect is entirely comparable to the "fewer trains" effect.
>

Your first sentence is correct. I erred in claiming direct 
proportionality. My point is that a plane carrying more people uses more 
fuel and thus produces more CO2. This is much less true for trains.

There are more direct consequences of individuals choosing to fly simply 
because weight added to an airplane has a much greater effect on energy 
consumption than weight added to a train. Things like luggage and 
airplane meals add weight, which requires more fuel, which then requires 
even more fuel. So there are direct consequences with actually boarding 
an airplane more so than with trains.

Whether or not reducing the number of overall passengers has the same 
effect on planes as it does on trains is a really complicated and 
difficult question to answer. You get into stuff like futures pricing of 
jet fuel and regulations governing rescheduling practices, etc. I 
don’t think anyone on this list is qualified enough to answer this 
question.

—Andrew