I heard Jeffrey Sachs saying the same thing you say: tax at the point of mining, not at the point of emission. He then went on to explain that the current focu

I heard Jeffrey Sachs saying the same thing you say: tax at the point of mining, not at the point of emission. He then went on to explain that the current focus on emissions comes from the fact that some laws or proposals regarding CO2 (carbon credits) were, without much reflection, copied from corresponding regulations about sulfur, and for sulfur you are stuck with emissions because you don't mine sulfur.