Scientific American: If you tried to dump harmful waste on the property next door, your neighbor would either stop you or require you to pay a fee. But if you dump carbon dioxide into the air, no one charges you a penny because no one, as yet, owns the air. This free ride results in what economists call a market failure. The actual costs of polluting the atmosphere are enormous, but polluters don’t pay them. Instead future generations are stuck with the tab. A carbon tax, or a carbon cap-and-trade system, …