Well, aviation has grown, and it's now too large for its harms to be ignored.
This tax would increase the price of fuel by 20 percent (it now averages $0.50/liter worldwide) and thus the cost of flying.
Such a price increase will be unpopular with airlines that want everyone flying all the time (it's their business after all), but it would also have three positive effects:*
- The amount of fuel used would drop by a bit as airlines try to find ways to reduce this cost and some people decide not to fly. Both of these changes are good for reducing high-altitude (and more harmful) GHG emissions.
- Innovators and airlines would work harder to reduce fossil-based energy sources in planes. Such switches might occur via bio-fuels or "electric planes" but my bet is that hybrids (jetfuel for takeoff; electric for cruising) would be first to market.
- Governments with the potential to earn money from the tax (approximately $20 billion per year) will compete to provide quality fueling services. (There's a risk they will also compete to lower the tax back to zero, but that can be limited by, e.g., sharing tax revenue evenly among departure and destination airports.) Want more? Read this pdf.
* Most of this logic also applies to ship fuel, but there are many more ships burning a much larger range of fuels with technology that's harder (IMO) to switch over to clean energy.