The worst case scenario is still a mass extinction event unlike anything witnessed by the human species, plus global food and water shortages, and certain areas of the world becoming unsuitable for human life during the hot months.
That means mass migration and conflict over resources, and a deteriorating ecosystem that we still very much rely on to produce food and healthy living conditions.
Basically, scenario 4 or 5 outlined in that article is what I see happening. Sure, it's not a guaranteed extinction, but it will devastating, and it's far more likely than a GAI takeover.
It’s been a while since I looked at IPCC report. Is the worst case still apocalyptically bad? We’re nearing 1.5 degrees above average and the results are bad enough already. (Not looking forward to another summer of fires like Australia had a couple of years ago.)
We're still not only increasing emissions, but accelerating the increasing emissions. I don't think we'll avoid a rise of 4 degrees over the average.
On the bright side we may have killed the cycles of glaciation that would have been awkward in the future, to put it mildly. The cost is going to be so heavy though.
