Last week, one of the world’s seven fossil fuel supermajors — Britsh Petroleum, announced, in essence, that the time had come to wind down its core business. What makes BP’s plan so important is the scale and especially the speed of the cuts it envisions. 2030 is the new 2050; it represents, says the U.N.’s climate panel, a real deadline in the effort to meet the climate targets agreed in Paris in 2015.