Actually what happens if EU decided to make an CO2 import tax om all wares produced in countries who don't lower their CO2 levels to the same as EU ?
All countries dependent on EU would have to lower CO2 emissions too. Thus most countries in the world would do the same as EU to make sure other countries dont get trade advantages from them and also force their import goods to have a low impact CO2 footprint.
Thus everyone will be forced to do it. Just because EU is such a big and important importer of goods.