Defining "properly" when related to taxes is too difficult for a HN comment. Also, I'm neither a climate scientist nor do I consider myself an expert in economy. I'm rather concerned about climate change, so my numbers would likely be much higher than necessary.

But I'd suggest putting a bunch of scientists in a room for a while to figure out the environmental impact and define some acceptable limit of yearly pollution. Then raise taxes until we're under the limit. Or something similar.

Have them do it every 2 years to account for changing science.

Of course, then you have a de facto regulatory body, which everyone hates, and thus a new problem.

Sounds good to me.

Properly, in this context, simply means tax it like you tax fuel/energy for other modes of transportation.

Airlines have been very successful at getting special treatment by scaremongering "no more connections for you". Which is certainly a mostly empty threat, because connections will only go down by as much as demand elasticity reacts to the price difference.

Difficult to define it, but we can be pretty sure we're nowhere close with our current tax policies.

In theory you set the tax rate to counteract the net negative externalities. It's estimating those externalities that's the source of contention (as you hint at re: feedback loops). So assign ten teams to estimate it and take the median?