When it comes to reducing personal environmental impact in any sphere (pollution, climate change, resource depletion, etc), there comes a point where each individual says: “That is too great a sacrifice.” Some people would refuse to give up incandescent bulbs; some, eating meat; some, driving their cars; some, flying in jets. The question arises of what to do when there is a fundamental conflict between an ethical requirement and a person’s will. In the modern world, this applies perhaps most harshly to air travel.
We know that very substantial emissions are associated with flying. We also know that substantial emissions will definitely cause human suffering and death in the future. One flight emits significantly more than a single person can sustainably emit in a year. Every year emissions are above sustainable levels, the concentration of greenhouse gases rises; each year in which that happens, the mean energy absorbed by the planet increases. At some point in the future, it is inevitable that this process would cause massive harm to human beings and non-human living things. It is also plausible that positive feedbacks could create abrupt or runaway climate change, either of which could cause human extinction or the end of humanity as a species with civilization. In the face of that, it is difficult to say that flying isn’t morally wrong.
At the same time, it is impossible for most people to say it is. Partly, this is because of a failure of imagination. They cannot imagine a world where people don’t fly. Mostly, though, it is reflective of the powerful kind of denial that lets people continue to live as they do, even when convincing evidence of the wrongness of their behaviour is revealed. Rationalizations are myriad: (a) Why should I stop when others will just continue? (b) There has to be a balance between acting ethically and getting what I want. Neither of these has any ethical strength in the face of a known and significant wrong. At the same time, it is implausible that people will abandon their self-deception or that external forces will constrain their behaviour effectively. If that is true, our future really isn’t in our hands. We are slaves to fate, in terms of what technological innovation might bring and in terms of how sensitive the climate really is to greenhouse gasses.