Well the idea of a carbon tax, in the context of effects which are difficult to determine, is that it is simple and specifically does not attempt to determine those effects. It relies on the assumption that less carbon release is better, and after that, all the determinations about what specifically can be changed to reduce carbon usage is handled by the distributed decision mechanism of the market.
The difficulty in evaluating these effects isn’t just an obstacle to be overcome, but a design reality that determines the shape of a solution.
Specifically, it means the potential solution should not include that evaluation happening inside the government. That evaluation should be done by the more inclusive and thorough mechanisms of market interaction, rather than the shallow and cursory mechanisms of committee meetings.