Any reasonable effective top-down action on climate change would require significant short-term restrictions on how common people live their lives - either as direct prohibitions or through taxation e.g. pricing in environmental externalities.

A political leader who'd force their nation "go full green" would be ousted at the next election, if not quicker - immediate riots on the streets would be likely.

One of the triggers for gilets jaunes in France was a comparably tiny fuel eco-tax - can you imagine the effect of a taxation that's intented to meaningfully decrease consumption; an eco-tax so large not that people pay more and whine at increased prices but that many of them would actually be forced to stop eating beef and driving cars because they can't afford it? Most of the population currently doesn't want such restrictions and the political leaders won't force them to.