The bottom line for climate changers is this:
make carbon-based energy expensive so alternative energy production "seems" cheap by comparison. Note this makes energy cheaper only in a relative sense. The rest of the plan is to redistribute wealth to the poor who without subsidies could not afford to use the energy they once did.
They are essentially trying to create a real demand for alternative energy production by artificially raising the cost of carbon-based energy.
Compensating for negative externalities inherent to forms of energy that release large amounts of carbon dioxide is not "artificially raising the cost of carbon based energy." It is assigning its actual cost to it.