I heard “personal carbon allowances” mentioned recently, and hadn’t heard of it before, so I grabbed this from Wikipedia:

Personal carbon trading is the generic term for a number of proposed emissions trading schemes under which emissions credits would be allocated to adult individuals on a (broadly) equal per capita basis, within national carbon budgets.^[1] Individuals then surrender these credits when buying fuel or electricity. Individuals wanting or needing to emit at a level above that permitted by their initial allocation would be able to purchase additional credits from those using less, creating a profit for those individuals who emit at a level below that permitted by their initial allocation.

Sounds good in principle, although I think a carbon-based sales tax would be simpler and more straightforward. This concept assumes that people have time and motivation to sit around, do research, make rational choices, and engage in transactions to maximize financial gain. Busy people balancing careers, families, and the minuscule leisure time left over don’t necessarily have time to do this. For this to work, I think it would have to be pretty automated. Maybe a future of automated, computer-controlled financial transactions and markets could pull this off.