Weighted means we should consider them differently. 1 tonne of CO2 produced when you have no idea what global warming is hits very different to 1 tonne of CO2 produced when you've known about global warming for 60 years and the entire world has come together and said lets start trying to reduce emissions.

If at that point you start slapping down 60 coal plants and moon shotting your co2 pollution then you should be blamed for global warming.

So whoever industrialises before there's scientific consensus on climate change gets to keep the benefits of their pollution and those who don't have to somehow skip that part of the tech tree and jump straight to renewables/nuclear?

I can see why the countries that were not first to industrialise are not on board with that idea.