Satellites etc. track which country emits how much CO2 and give the result e.g. every week to an assembly where every nation looks at its collected data (can be done fully automatically as well).
Current tracking technology, assuming that you're talking about NASA's only tracks localized emissions and is actually not accurate enough. We are still far from tracking verifiable CO2 emission of an entire country accurately.Every nation has its own anonymous key to a multi-sig wallet (e.g. 150/195 wallet). If the data of a nation from step 2 comes to the conclusion, that another nation emitted more than it has certificates, it can sign a transaction on the multi-sig wallet to move the according pledge from the nation who emitted too much CO2 to the rest of the nations who emitted less than it actually needed. This forms the consensus mechanism. As the votes are anonymous and the CO2 source location are transparent.
Transaction has to be initiated by someone, and signed by others. It would be clear who initiated and signed it.By and large, ratified climate change agreements are without teeth and it is as good as nothing. Whilst there are significant improvement in the shift to cleaner energy and certain countries having made significant progress to reduce carbon emissions, we should also acknowledge that there is still a good portion of the countries that isn't compliant with the agreement and merely treating it as a lipservice.
Beyond thinking about whether Bitcoin can even serve as an incentive for countries to do so (remember 500 billion isn't enough to cover a lot of the GDP of the worlds' largest economy), we have to first consider if we can even have the countries agree to put their funds into a locked account all together.
