The world urgently needs to expand its use of carbon prices

IF ECONOMISTS ruled the world, carbon prices would drive most of the action on climate change. Polluters would pay for the negative externality their emissions inflict on the planet. There might be differences on the method of payment—some might lean more towards taxes, others towards the permits used in “cap and trade” schemes. But the idea that some sort of price would help people find an efficient means of reducing emissions is a given.