I’ve been thinking a lot about travel providers seeking cost savings and cynically selling it with environmental claims. And I’ve been thinking about real environmental issues too. What do we owe future generations of people who do not exist today? What sorts of actions do we take today based on imperfect information?

These are all hard questions I think. And even when we figure it out the world is a lot more complicated than we often think of it. After all, as I contemplate fatherhood, isn’t having children the worst thing you can do for the environment, given the resources that will be consumed over their lifetime? And while most cars may burn fossil fuels, walking burns calories — and if you replace those calories with meat aren’t you doing something even worse for the environment than driving?

Similarly I think flying is complicated. Air travel emits carbon dioxide. More demand for air travel supports more flights, and thus more carbon dioxide emissions.

While the interaction of emissions and temperature change is complex, the particular mechanisms subject to debate amongst scientists, a simple model suggests that your air travel is bad for the environment. That may not hold in every case, and it’s highly unlikely that any one individual’s actions change airline schedules enough or that even if they did that incremental change would be noticeable enough even in the most advanced models. But taken together air travel is thought to be a negative for climate. So you get the blame.

It simply isn’t true though that every airline passenger and every ticket has the same contribution to emissions.

And we do know whether you have a high – or an exceptionally low – probability of affecting the number of flights, size of aircraft, and thus emissions.

• If you’re pulling inventory out of a low fare bucket, the strong expectation is that there’s little effect at the margin on your buying the ticket because the airline expects to operate a flight that doesn’t come close to filling up. You aren’t going to cause there to be an extra flight.

• If you’re pulling inventory out of a high fare bucket, if you’re traveling on a full Y fare, you can pretty much expect that the flight will be close to sold out (or that they’ll be flying it because of a small number of passengers like you). The airline may even be willing to risk displacing another passenger in the short term in exchange for your higher fare… and your ticket cost is high enough to potentially influence behavior on the part of the airline.

As a full fare passenger you’re part of a small subgroup of passengers paying the highest fares that airlines crave and will make their decisions based on the relative mix of such passengers rather than on passengers as a whole.

In contrast, if you’re in a low fare bucket the airline is scooping up some incremental revenue for a flight they’re planning to operate for other reasons.

Reality is even a little bit more complicated than that. Cargo has to come into play, too (especially on international routes). Regardless of what you pay and what fare class you’re booking in, there are flights that operate because of cargo and not because of passengers, the passengers are all at the margin.

If you’re traveling on an award ticket at the saver level that’s the extreme limit of the belief on the part of the airline that they would (a) otherwise operate the flight and (b) that your seat would go unsold.

If you are traveling on saver-level award tickets you can be quite confident your environmental impact is quite small, limited for the most part to the extra fuel resulting from your extra weight on board the aircraft (and quite possibly outweighed by the fuel you’d be consuming in your car were you not flying that day).

Quite simply, award passengers aren’t contributing to an airline’s decision to operate more flights and generate greater emissions except years ago when Air Canada ran Hawaii flights only for loyalty program members.

It does seem that the better deal you get on your ticket, the better you can feel about the environmental impact of your travel.