But what I will not admit – and what none of us should ever admit – is defeat because we have not failed to reduce greenhouse gas emissions. The truth is, until recently, we never really tried. As John Paul Jones is supposed to have said during the American Revolution, “I have not yet begun to fight!”

For this reason, despite the enormous challenge, we should be undaunted. We should be eager to throw ourselves to the task. There is another American revolution afoot: a low-carbon revolution.