Also consider climate cycles such as ice ages. Imagine a coalition finds a wildy successful heat reduction strategy and it impacts well beyond what was anticipated? How would things go if we accelerrated glaciation down to the gulf of Mexico? The Earth’s wobble and axial tilt are part of this process over incredible periods of time… CFC’s and the ozone are a good example of rapid and unanticipated results of human inputs. No easy answer even with stakes as high as they appear.
I’m not arguing to do nothing, just attempting some clarity on the broader strokes of the issues. Much of our understandings of natural processes are still immature and incomplete - appreciating that fact should be a guiding principle for any near-to-hand actions.