The back story to Mr. Putin’s move is a stagnation in global consumption that has turned into an outright downturn due to the novel coronavirus. As de facto chief of the Organization of Petroleum Exporting Countries (OPEC), Saudi Arabia tried to persuade Mr. Putin to cut its production in tandem with the cartel, so as to prop up prices for them all. When he refused, Saudi Crown Prince Mohammed bin Salman countered by declaring his country would run its industry at maximum output for the foreseeable future. So far, Russia has not bowed to the pressure, partly because Moscow can balance its budget at a much lower price of oil than Saudi Arabia can, and partly because Mr. Putin smells an opportunity to get even with the United States. Russia’s oil-exporting partners Venezuela and Iran, already reeling from political unrest and the coronavirus, respectively, are likely to take politically destabilizing hits as a consequence, but apparently those are lower priorities for Moscow.
President Trump’s immediate response to all of this was to celebrate lower prices at the gas pump, which does indeed amount to a tax cut for U.S. consumers. The problem is that what the United States may gain in consumer purchasing power it will lose in financial-system instability, as the oil patch’s problems spread to their creditors and stockholders on Wall Street. There may be a double-edged impact on the climate, too, since greenhouse-gas emissions go up due to extra consumption of cheaper oil — and go down when production falls in U.S. oil fields. As both a colossal consumer and a colossal producer of oil for the foreseeable future, the United States is on both sides of the world’s biggest trade-off, both economically and environmentally. A tax on carbon would enable us to control climate risks no matter which way the markets move.