If CO2 emissions don’t peak until then, the feedback mechanisms will kick in and Earth will enter runaway climate change, global meltdown, leading to Venus syndrome.
Don’t ask me how I know that. It’s a secret. I can’t tell you right now.
I may be wrong. That would of course mean that humanity might peak out earlier than absolutely necessary. The real deadline may be 18:00, not 17:30.
But on the other hand, there would be nothing wrong with peaking out early. The stakes are high. You really want to avoid Venus syndrome. It is the equivalent of a large asteroid hit, wiping out all life. I for one think it would be a prudent course of action to peak out at the earliest possible point in time, and then reduce quickly, and then quickly start going negative, sucking all the mess up from the atmosphere.