That's why I don't claim to be a scientist when you ask me to explain to you how we know CO comes from a particular country
I never asked you how we know. It's fairly simple to identify by production capability how much Carbon any single nation produces.
What I asked was, 'How does the atmosphere know?'.
Since it clearly doesn't, the nation from which Carbon emits bears no relation to the overall amount of Carbon in the air.
If the amount of Carbon in the air is important to a country, they should definitely take steps to reduce it.
However, American voters don't appear to be particularly interested in the subject either way. In America, it's the voters who choose the agendas, ultimately.