Not on a per person basis. China also does the most to combat climate change, purely by virtue of its population. It also does the most research, has the most homed people, has the most fed people, delivers the most babies etc etc.

When dealing with different countries with wildly different populations, it's the amount per person and change per person that counts the most.

Unfortunately, by dividing by country, it becomes a game theory problem in that the actions you do don't have an effect. It's collective actions that work. As this becomes more imperative, the cost of those not acting will not be borne by countries that are and they will be punished in trade tariffs.