Grist: These days, its common to hear a politician, an economist, or even an oil company profess that pricing carbon is the most efficient way to combat climate change. But real-life climate policy is often far from efficient; were left settling for second-best (or third- or fourth-best) solutions. In the run-up to the Paris climate talks at the end of this year, a fair question then is whether or not we can expect any kind of global carbon pricing mechanism to emerge from the negotiations. Spoiler alert:...