You're talking about creating a carbon currency. ACCU's can be traded to anyone but their value is only held in Australia. I just assisted an LGA to sell a dozen of them, and there are global companies that made bids through the platform.
For them to be globally valued they would essentially become a currency. Potentially block chain technology may assist in this occurring in the future.
The issue would be its relative value in each country.
But suggesting we will get anything imposed on us is laughable. We are a small blip in global emissions.
