I decided to fly as little as possible in 2017, once I realised the tremendous greenhouse gas emissions a flight releases. It really only contributes a small amount of total global emissions due to the privileged position one needs to be able to fly, and it is a prime example of our unjust culture of over-consumption at the expense of others.
Since then I have visited few European countries for scientific conferences, a work trip, and a family matter (these are France, Germany, Czechia, Poland, and Italy). It goes without saying that the journeys take longer, but the real obstacle is the prohibitive prices of many routes. I had to carefully select the times I travelled to get the cheapest options which made them much less comfortable than they could be. This includes overnight coaches over the English Channel and waiting for trains in the middle of the night, which meant being sleep deprived for the rest of the journey. And still the flights cost less.
On the other hand, it gave me the opportunity to see several cities, albeit briefly, that I wouldn’t have seen otherwise, and the actual journey itself by train is vastly more comfortable than flying. If the prices were comparable, and people had the extra travel time needed, it is an easy sell. More room, the ability to freely walk around, better scenery, no cabin pressurisation, and wifi are some obvious advantages of good trains. This all being said, even trains and coaches emit greenhouses gases (both in usage and production), for us to be sustainable, really all unsustainable travel needs to be minimised. The substitution of fossil fuel to renewable has to go hand in hand with much less energy consumption so that supply can adequately match demand. Unsustainable travel in general is glamorised when it really should not be.
It still is a part of our over-consumption and it pains me to see that the fellow scientists around me do not view it that way, but as something to aspire to. What that means for scientific conferences, I do not know. One thing that could be happening right now is to strategically select conference locations to minimise the total travel needed for participants.
I work in the ExoMol group which generates high resolution molecular line lists at high temperatures. These are primarily used to determine the composition of exoplanetary atmospheres.