If people stop or reduce flying one by one there's clearly some point at which a stepwise reduction in service occurs. Your are unlikely to be the person who triggers this but the reduction will also be proportionately larger than your contribution too. So you should think of yourself as reducing carbon emissions by the person-mile amount in expectation even if it will never actually be that amount.
Or to frame it another way, when you fly you're playing Russian roulette with adding an amount of CO2 to the atmosphere dwarfing anything else you might be causing.
Or to frame it another way, when you fly you're playing Russian roulette with adding an amount of CO2 to the atmosphere dwarfing anything else you might be causing.