Think globally, act locally, they used to say. If it’s true, why does it matter that the US has — again — withdrawn support for international co-ordination on climate change? In the mid-20th century, the US emitted about as much carbon dioxide as every other country in the world combined. Now its share of global emissions is less than 15 per cent. It is a shame that the US administration can’t take climate change seriously, although a solid majority of Americans are concerned about the issue. But even without them, why can’t the rest of us just “act locally”?

That might seem a foolish question. The US stance undermines global agreement, and global agreement is important because climate change poses a collective action problem. Greenhouse gases emitted anywhere in the world, by anyone, mix in the atmosphere and contribute to the general problem of a warming world.

It’s a little like splitting a restaurant bill between a large group. Order the Wagyu steak and vintage champagne, why not?