angelorange,
What better incentive on aviation to get it's arse in to gear reducing emissions than a massive tax that threatening its very survival? This is the argument put forward for how we will suddenly develop a replacement for hyrdocarbon consumption - and the justification for why we don't do sod all about it right now.
A properly invested tax will have a very positive effect if put into public and private R&D. If left to the airlines and manufacturers themselves any extra money will simply be thrown back to shareholders. That can hardly be seen as a better way of improving emissions efficiency.
As for the industry being at the forefront of technology, the unfortunate side is it hasn't been enough. Reductions in turbine pollution are indeed occurring, but they are outstripped by the pace of expansion in the airline industry. As such, aircraft emissions are set to increase year on year despite technological improvements. Only by reducing the use of air travel can this even be stabalised - nto that stabalisation itself is even enough.
Biofuels are a dead end. The environmental impact of their creation is as destructive as the carbon emissions we presently produce.