Like you I am frequently asked similar questions. But since my entire work is concerned with trying to conserve what is left of the world's natural carbon storehouses, whether it's rainforest or Dry Chaco, or regenerating forests, I don't see to much hypocricy in travel to implement the projects. On a personal level, I have made the biggest contribution an individual can make, and that was voluntary sterilization before reproduction. The effect on future carbon emmissions is incalculable. Let's not beat about the bush. Flying is not the problem, it's a symptom. Breeding more humans is the real problem.