What some of the other comments here seem to miss is that he isn't suggesting to replace air travel with other modes of transport. He suggests cutting back on u

What some of the other comments here seem to miss is that he isn't suggesting to replace air travel with other modes of transport. He suggests cutting back on unnecessary long distance travel. And if you have ever seen scientists' travel schedules, you might be inclined to agree. I find it bizarre that those people who should be the first to understand climate change are among the most active producers of CO2. As a grad student I once flew half way around the world (18 hours + 2 hours flight time) to present a paper to a room of 10 people who had traveled similar distances to get there. Because the paper was more or less mistakenly assigned to a "robots for hazardous environments" session, exactly none of the people in the audience cared. And because I was last to present in a session of 6 presentations and the 5th presenter didn't show up, I started mine ahead of schedule. A few acquaintances who wanted to stop by just to see me present came in just after I finished. Nobody gained anything from this 15 minute presentation. If I had skipped the trip, my paper would not have been included in the conference proceedings. Publishing papers at conferences is one thing you have to do to be considered a successful scientist and this was only my second conference paper. The story is only one anecdote, but the entire system of science is built around encouraging people to travel long distances frequently. It's stupid.