Central planning across a large geography failed miserably and killed hundreds of millions in the 20th century. I'll take hundreds of localized solutions/experiments any day thanks.
The United States government has been extremely successful as the central point of authority of the 50 states.
Central planning has been extremely successful in lifting hundreds of millions of people out of poverty in China, and making China a superpower. And, I shall add, a superpower that's now remained in existence (73 years) longer than the Soviet Union did (70 years).
I'm all for local experimentation, but not for local authority to block progress for all, like countries not doing anything about the climate crisis.
China has enjoyed a huge trade imbalance from a one sided take on globalization. Should we all strive for China's approach to the climate crisis? Should we ask the 12 million Uyghurs how things are going?
The United States government does very little central planning.
And, you point out the (economic) success of China, and then complain about countries not doing anything about the climate crisis. Have you looked at China's CO2 emissions? Yes, they bootstrapped their economy. The environmental cost has been pretty steep, though...
Humanity's problems just not getting solved, short of a miracle engineering breakthrough, is more likely than all the nuclear states aggreeing to form one government. So here's hoping there is actually an illuminati running everything, I suppose.