When going from A to D some times you need to transit in B and even C. Price match the most eco-friendly with the cheapest alternative in points.

For flights with a lot of empty seats, open more award seats short time before departure.

Using hydrogen tanks in the rear of the plane, for example. This could work on shorter routes such as domestic flights or intra-Europe.

Pay for luggage by weight.

Charging mobile phones or other equipment from sunlight in the sky. «Day flights are always sunny»

Change the paper dispensers in the lavatories, often many tissues come at a time. Get single tissue dispensers. Save paper and avoid overfilled bins that looks untidy.