Respectable scientists try not to be alarmists. I got interested in Thwaites when I heard Richard Alley say it was something like "50 years give or take 50 years." Maybe it was somewhere in this talk:
but he has moderated his language somewhat since then to say that there is a risk that it could happen in decades but it may never happen. More of a risk analysis rather than a prediction.
On the other hand, a paper published last December tried to model the collapse of Thwaites and it didn't see anything major for 30 years and the 100 year predictions were for something like a contribution of only 8 inches of sea level.
https://www.the-cryosphere.net/12/3861/2018/But if you read the paper, under section 4.6 "Limitations of the model study" you find "Another limitation is that the ice shelf front migration is not included in our simulations. We assume that the ice shelf front position of TG remains fixed" and later "The eastern ice shelf has been thinning and retreating, which means that the ice shelf could disintegrate in the coming decades."
It is hard to understand exactly what they are saying here. They are making 100 year predictions assuming that the Eastern Ice Shelf remains fixed, yet they freely admit that the Eastern Ice Shelf could disintegrate in the coming decades.
Anyone who looks closely, knows that the Thwaites Eastern Ice Shelf (TEIS) is doomed to collapse in the next ten years. The ice is visibly sliding eastward off the forward buttress which is at an angle to the current ice movement and not in a position to stop the forward progress. (See GIF below.) Meanwhile, the ice on the Western side of the TEIS has broken away (including the "cork" above) leaving no new ice to form a replacement TEIS. It's impossible to say if the ice further inland might reform TEIS a few years after the collapse, but in my mind it is hard to find solace in these 100 year models based on the "stability" of the TEIS.
The models say that the Eastern half of Thwaites is the one most likely to collapse first, but the Eastern half is currently buttressed by the TEIS. If the TEIS collapses and the Eastern half starts moving as fast as the Western half is currently, about 5km/year, I don't see how these 100 year predictions are worth anything.
The academic push has been to say "let's really study Thwaites" and they've done one season of observations so far. Over the next 5 years expect to see a lot more papers published, but in the mean time, all we can do is watch the ice.