What use is years and years worth of scientific research and intelligence if all it does is cause our own extinction? We are just like Ouroboros eating its own tail.
Human constructs and social endeavors are centralized because the network effect matters.
Even worse, authorities across the world are collectively cutting down about 15 billion trees per year, split roughly evenly across permanent deforestation, shifting agriculture (conversion of forest for farming), and logging: https://ourworldindata.org/deforestation#not-all-forest-loss...
But today we see exactly the opposite. That countries do not have a right for self determination and that unelected bodies can dictate form afar what countries should do whether or not they are signatories to an agreement or not. That imposition of extra national law is imperialism --not by a country but by elite leadership. If we were to vote democratically from one global pool of voters, would we agree to what the masses from those countries vote for?
I think there is plenty of reason for both pessimism and optimism, and plenty of reasons for neither.