&gt; Flying is one of the human activities that we don&#x27;t have to do<p>I think this needs to be approached as a matter of degree, not a blanket statement. Some flying saves lives directly: Medical evacs, the military, etc. Some is worthwhile. The question is, where do we draw the line?<p>Is it worth it for climate scientists to fly to a conference that will accelerate progress on climate change? Is it worth it for someone to fly to see their elderly parents? To woo someone they are likely to marry, providing a lifetime bond for two people, and possibly making new people? To fly to the Olympics as a spectator? For what purposes is telepresence a sufficient substitute?<p>I think the threshold should be raised much higher and climate change needs to be addressed as a crisis. Even people who believe the science seem to not quite embrace the changes that need to be made; there is a lack of leadership setting new standards and telling people the hard facts: When is flying worthwhile? This study of this question, and many others like it, should be mature and well-known and not a relatively novel idea on HN.