Although widely encouraged by economists - including within the Congressional Budget Office - who say it's a more efficient and direct approach to cutting emissions, the carbon tax has been largely shunned by most lawmakers as it's seen as politically unfeasible to pass. That may be why Exxon has joined the ranks of other heavy carbon emitters calling for a carbon tax, as it would reveal more transparently of the actual costs to the economy of putting a premium on greenhouse gas emissions.
