Although a global, consensus-based action may the most effective approach to mitigate and adapt to global heating, this is not how social transformations happen.
In reality, consensus-based approaches (cf UNFCCC) will fail, because those benefitting from the current system will have a vital conflict with those who are or will be suffering from global heating, and veto change. For example, a consensus-based approach THAT racism is morally wrong and HOW to abolish it will fail. There are always some outcasts (activists) needed, who are initially ignored and laughed at, to constantly question the system and trigger change.
In addition, the framing “Global problems, need global solutions!” is a logical fallacy because the source of the problem of the climate crisis is mostly local (global north, fossil industry). A better illustration of this fallacy is maybe, that a single source of CFCs can destroy the ozone layer globally. Is there still a global solution needed? Or is this just smart framing to dilute responsibility?
“Never doubt that a small group of thoughtful, committed, citizens can change the world. Indeed, it is the only thing that ever has.” ― Margaret Mead