Acting alone would be pointless, skeptics say. Indeed, China is now by far the world’s biggest carbon emitter, with the United States second and India a fast-rising third. What would be the point of going to great effort to reduce U.S. emissions while others just burn more coal?

Think about it, though. We are, after all, the second-biggest emitter, which means that any substantial reduction would indeed have measurable impact. Also, officials in China and India, unlike those in the Trump administration, understand and accept the conclusions of climate scientists. China may be adding coal-fired power plants, but it is also making massive investments in clean energy. Do you really want Beijing to lead the way into the future? Shouldn’t it be Washington?

That’s a rationale for the Green New Deal that the Make America Great Again crowd should embrace. If you believe in American exceptionalism, you believe that the United States has a duty to lead at moments of crisis. This is such a moment.