We've been seeing events happen more and more with quotes from scientists saying "This wasn't expected to happen for another 50 years" [according to the IPCC reports].
Additionally, the IPCC notoriously makes their predictions algorithmically based purely on existing observations and doesn't take feedback loops into account. Those feedback loops are nearly guaranteed, but since they haven't been triggered yet, the extent of the feedback is hard to predict and thus is ignored.
It's because of these things that I tend to think that the IPCC reports are milquetoast. Even though they shock the public, they're actually doing a disservice by making people think they have more time than they actually have.
Plus, even if it was correct, most people will see this headline and think that we have 80 years to fix the problem and not realize that the bulk of the melting will take place before the 80 years is up.
My non-scientific rule-of-thumb with IPCC reports is to take the time and divide it by 10 as the lower boundary and by 5 as the upper boundary. This is to take into account the "1 in a 1000 year events" that seem to occur every few years now.
I personally expect the Kush-Himalaya ice sheet melt to be complete between 8 and 16 years from now because of a drastic and "unforeseen" weather event that accelerates it one year, like a stalled heat "blob" that camps over it for a season or a season of above-freezing rain that carves up the ice and carries it as melt-water downriver.