It’s shaping up to be a crucial week in climate politics.
At the centre stands the EU, cast, in this guise, as climate champion - determined to take a small step towards charging airlines for the full environmental costs of flying, and to tax highly-polluting forms of fossil fuels.
Attacking the EU from every side is a large number of countries with serious clout.
If the EU is successful on either of these issues, it opens the door to other measures.
One idea that’s been batted around for years is some kind of border adjustment.
So country A levies charges on emissions from companies making a certain type of goods.
Country B doesn’t have any such charges. So when Country A imports that type of goods from Country B, it imposes a tariff to compensate.
You can see immediately why it’s controversial; not least because if such measures came into use for climate change, might countries also try to impose them for other reasons? How far would it go before it became protectionism?
That’s why all kinds of observers from environment groups and business lobbies will be watching this week’s events like hawks.