a) The transition to clean energy, transportation etc by Western countries funds the development and investment in new technologies. These then filter down to developing countries when the economies of scale kick in e.g. solar panels, electric cars.
b) There are also other benefits to cleaner solutions than just trying to achieve net-zero. Reductions in pollution reduce morbidity, improve productivity, improve happiness, secure food supply etc.
I think you overestimate the importance of what the West does. The West no longer dominates the world economically. Things no longer filter down the rest of the world as simply as you think. China is a bigger economy than any Western economy than the US, and is growing. India is about as big as any European economy. Both, and many other countries are doing more and more of their own R & D and have their own agendas.
The West still leads in overall R&D. Even TSMC advanced nodes ultimately rely on western equipment and technology. New advancements in AI and vaccines were western as well.
China has made impressive bounds in R&D but still lags in many fields of scientific research. Much of their research output is derivative in my experience of reading a fair bit of research articles in several fields.
However China does lead in many fields of manufacturing. The western countries are far behind in there. That is important in terms of global leadership in renewable energy.
So you have to count the EU as a single country to push China into third place. This is something people argue about. During Brexit I many people assured me the EU was not a country.
If you use PPP rather than nominal GDP China is actually the biggest and the EU the third biggest.
Also worth noting that, despite expansion, the EU was a smaller proportion of the worth economy before the UK left, than the EEC was after Britain joined. The trend is very much away from the West.
Their population is stagnating and there's some good signs that the numbers they gave were not accurate in the first place, China's real population is likely lower than India.
a) The transition to clean energy, transportation etc by Western countries funds the development and investment in new technologies. These then filter down to developing countries when the economies of scale kick in e.g. solar panels, electric cars.
b) There are also other benefits to cleaner solutions than just trying to achieve net-zero. Reductions in pollution reduce morbidity, improve productivity, improve happiness, secure food supply etc.