It depends on who you are. The median person doesn't fly. But a round trip flight from Shanghai to New York is 3.4 tons of carbon, pretty close to the average global anual per capita emissions of 4.0 tons.
When the op says, "we should focus on…" I assume he's talking about policy, technology, etc., not individual concessions.
The best argument I can imagine for encouraging individual concessions is that, if the campaign to do so is massively successful, it might create a new norm, which will increase public awareness, which will increase public support for new policies and participation in the development of new technologies. But imo that's an unnecessarily roundabout course to chart.
I’m not saying that is or isn’t my perspective, just pointing out that it is a perspective that may hold some validity.
But I do think it's very easy to get sucked into a mindset of, "Let's shame individuals into making sacrifices," without actually doing the math on whether or not that's an effective approach.
I agree that flights are perhaps not the most urgent issue. But encouraging people to fly more is still wrong. When possible, we should avoid flights.
Someone I know got denied boarding a flight on employee standby (~free ticket, family member works for the airline) because they needed the weight for cargo.
You'd think with this limit a leaner airline would come out with per-kg passenger surcharges?
Roughly half the takeoff weight of an airliner is fuel. The fuel burned on a continental-distance (3000+ km / 2000+ mile) flight is roughly equal to the passenger's weight. CO2 emissions by mass exceed the mass of the fuel by a factor of three, as you're adding the mass of the oxygen that's added, far more than the hydrogen that's split off.
https://www.engineeringtoolbox.com/co2-emission-fuels-d_1085...
For a 747, roughly, takeoff, climb and descent require a fixed share of fuel, 7840 kg, and take about 250km (30.1 kg/km), cruise, another 10.1 kg/km. Shorter flights are comparatively worse, but what gets you in long-haul flights is simply the total distance: about 12,000 km for each leg of that Shanghai-NYC trip. And that's allocated across about 420 passengers.
https://www.sciencefocus.com/future-technology/how-many-cars...
Back-of-the-envelope estimates: At Shanghai-NYC distances, that's 34,300 kg of fuel vs. about 420 * 100 kg/passenger total allowance (rough numbers), or roughly 3x the fuel mass per passenger, per leg, or 9x the CO2 emissions mass. That works out to about 1.8 tonnes based on my figures and maths, which is lower than your parent, but probably assumes too large a plane and too many passengers for a long-distance flight.
But yes: tonnes of CO2 emissions per passenger for round-trip international travel is about right.
That's sounds very low for fuel burn at that distance for a 747. The 747-8 carries over 191,000kg of fuel, yet has a maximum range of only 14,320km.
As an aside, I wonder if using "carbon" as shorthand for "carbon dioxide" does more harm than good.
The "carbon" vs. "fuel" vs. "CO2 emissions" terminology is legitimate -- these are all different real aspects of the phenomenon. Playing fast and loose between these, or simply confusing the terms (see also kW vs. kWh confusion in energy discussions) is far too common. I specifically called which of these I was using and how they're related.
Much of this would benefit by more use of tables and graphs and sensible comparisons, so that people are at least familiar with appearances. Understanding might or might not follow, but the journalistic practice of "tell a story around numbers without using numbers or pictures" seems to me actively harmful.