[Vesuvium]

In aviation, reducing fuel consumption has always been very important, since it's the most expensive part of flying.

The heavier a plane is, the more fuel it needs. But fuel has weight, too, which means you need even more fuel! Reducing fuel consumption translates to exponential operational savings.This is also why planes with batteries are problematic: batteries store much less energy per kg than fossil fuel. I doubt that the increased efficiency in going electric is going to offset the extra consumption due to the increased weight.

Even if they reduce emissions by 50% by 2050, flying will still produce ~5 more times CO2 than taking the train. And guess, what? The railway industry is also working to reduce emissions and with trains there's just so much more you can improve with much less investment.

By 2050, aviation might very well produce ~20 times the emissions of railways, even though it has halved its emissions.So, with our current knowledge, the best way to reduce aviation emissions is...taking the train.