We are watching the slow motion effects play out..
how severe they will become is not known.
how they will show themselves specifically and be able to forecast them, is not known.
In fact more frequently, normal weather that is to be expected is becoming more unpredictable.
The impact is impressive.
My country's east coast just being hit by a super storm the likes of which the planet hasn't seen in our human timeline with 130km hr winds ...that kind of damage is something.....
The "Son of the Blob" out here on my coast giving us mild summer temperatures in fall...and now heading towards winter with mild fall temperatures, while everywhere else between the two coasts of my country is getting beaten and buried by early snowfalls and snow storms...
for starters...
And that is just my country...

How bad do you think it can get Dave?
Double or triple your idea of "how bad it can get" and you are probably getting near "How bad it can get".

The absolute worst case scenario is climate tipping point reached, exceeded and runaway climate change heading to a planet that cannot sustain life ..."Earth gone rampant" ...another Venus..
That is the worst case scenario...
Everything less than that is still horrifically pretty bad.