Here are the ways I see airline industry produces pollution: * The airports are built (clearing so much green land, using so much concrete) * How flights taxi

Here are the ways I see airline industry produces pollution: * The airports are built (clearing so much green land, using so much concrete) * How flights taxi when on airport * How much time they spend in air due to congestion or weather * How far airports are located from city population centers and transportation between them. * Amount of time people spend at airports waiting - hence need large facilities to host them with food, entertainment (shopping) etc with air-conditioning. I can imagine ways of switching over to alternate fuels, optimizing the process flows to reduce fuel needed or avoid certain step entirely through innovation and drastic changes. But huge segment of travel generated pollution can be completed avoided by replacing in-person business meetings with alternate equally rich and rewarding experiences. In the future, some day, I hope there will be holographic rooms that one can use to holographically teleport to another location and do meetings as if they are there in person. This would consume way less energy and hence reduce pollution. Imagine "holo-portation" hotel rooms that you can rent for doing meetings.