I agree, our track record since the establishment of the IPCC has been only very slightly better than “business as usual” scenarios. The current decline of the AMOC current was not predicted to happen as quickly as it has, and the early 2000s IPCC reports didn’t even factor in Greenland ice sheet meltwater. I’m not a climate scientist, I think if we have one or two in this community, their input would be fascinating.
https://www.ipcc.ch/report/ar6/wg3/downloads/report/IPCC_AR6_WGIII_SummaryForPolicymakers.pdf - see Scenario C7 on page 19, 4 degrees is the current policy projection for 2100.