Worldwide treaty to impose import duty carbon tax based on average country-level per-capita emissions. So exports coming out of Australia or Canada would cost the most. These two countries lose their international competitive advantage. Companies in these countries get angry at their local government. Local government acts to reduce emissions.

A nice thing about this is it doesn't even punish poorer countries that much, despite the fact that they haven't transitioned as quickly as richer countries. Because they're poor, their economic activity is lower and they don't generate as much emissions, so the import duty would be lower.