This chapter examines the question of how aviation will address global warming and climate change. We have to do something, but first we need to spend more effort to understand the problem in a detailed way. If it seems that addressing all of the provisions of a sustainable approach will slow us down, we have to remember that if our actions are not sustainable, we will end up worse off than we are now. As for industry growth, it is difficult to settle on a pattern for the future. The chapter also explains a little bit about the mechanisms of global warming that bear on aviation's emissions profile, then give some size and shape to the effects created by CO₂ and other substances. It concludes with some data that deal with growth in global emissions from all sources so that we have a picture of aviation's possible relative contribution.