The missing thing: international incentive structures.

Today, most things are done the most economical way. And that might involve emitting carbon.

A country which regulates the emissions of carbon will end up producing goods and services using carbon free methods - but those methods will often be less economically efficient than the carbon producing method, even at scale.

So any country that goes all in on the carbon-free world will end up economically worse off -- it's goods won't be competitive in the global marketplace. A government cannot subsidize itself to competitiveness in all markets.

Solve that problem, and the world will decarbonize itself almost overnight.