I doubt that the following sentence.
China and India could have the greatest impact on stopping global warming.
In my opinion, when used with the phrase "have an impact on", the subject of the clause should be more specific, and "on stopping global warming" seems strange to me.
I should rewrite this: China and India would play a key role in global warming." or"China and India would be more responsible for global warming."
I'd appreciate it if you could answer me, and I'd like to know you great teachers' opinions.
Yes...the first is better I think. Both countries are in a period of rapid industrial growth and increasingly, the world's production is being moved to Asia. There is therefore a danger that a serious increase in global warming could easily happen if these manufacturers don't keep their production methods "clean". since they are increasingly responsible for world production, they could easily reduce global warming if they so desired.