I think those who dismiss the environmental effects of tankering outright are a bit short-sighted. I am a bit tired of the standard response "this is such a small issue. It makes very little difference in the grand scheme of things". Maybe true. But all the little areas where we waste resources combined do make a big difference. It's like every industry saying: "We only contribute x% to worldwide carbon emissions. Again, true, but if every single one of those industries cut their emissions by say 25% then the effect would be massive. And yes, Human consumption, animals etc emit a lot of carbon. But that should be no reason to not minimize emissions/use of finite resources were we can.
As an industry we have lot's of room for improvement without having to ban flying or making it prohibitively expensive. If, with the help of governments, we could fly optimum levels and direct routes more often, spend less time in holding and in queues for departure, and yes, perhaps had to tanker fuel less frequently, that would all help. Now, I'm sot suggesting airlines should be forced to buy expensive fuel instead of tankering, but if governments are serious about cutting emissions then maybe it should be illegal to sell fuel at such prices that economic tankering makes sense for the airline. Just a thought.