To further clarify, this is the research (from August 2025) which is cited in the CNN story which is the basis of the Dagens AI copypasta. "Shutdown of northern Atlantic overturning after 2100 following deep mixing collapse in CMIP6 projections".
The paper I cite is for sea level rise. IPCC models from 1990 and 2011 have made forecasts on sea level rise. When we compare those to what actually happened up to 2025, we see that we are slightly worse right now than their highest sea level prediction that was made.
We're worse than their worst case scenario, so their models were significantly too optimistic.
In the same paper, they also note that for temperature, the models have been accurate.
> When we compare those to what actually happened up to 2025, we see that we are slightly worse right now than their highest sea level prediction that was made.
No. The paper does not show that. Figure 3 shows that recent sea level rise, accounting for measurement uncertainty, is in line with projections of any of the models (around 2mm per year). In any case, they call out explicitly that the recent data is of insufficient duration to make the comparison you’re trying to make.
Temperature data in figure one is more or less exactly in the uncertainty window of the models (not shocking, considering that they’re calibrated to reproduce recent data).
I'm sorry, but I double checked and I do think you have it wrong. Figure 3 is for "sea level rise _rate_", and that one is indeed high but not significantly so.
Quoting "The satellite-based linear trend 1993–2011 is 3.2±
0.5 mm yr−1
, which is 60% faster than the best IPCC estimate
of 2.0 mm yr−1
for the same interval"
But, as the authors point out, the worst case forecasts that were within-data, are so for the wrong reasons. Quote "The model(s) defining the upper 95-percentile might
not get the right answer for the right reasons, but possibly by
overestimating past temperature rise."
My previous comment is regarding Figure 2, i.e. "Sea Level". I would invite you to read the whole paper. It is only 3 pages and written without jargon.
Sea level rise rate is what matters (we cannot measure “sea level” absolutely, and therefore must work in terms of relative rates of change). The authors explicitly tell you that the data is not sufficient to conclude what they’re alluding:
> this period is too short to determine meaningful changes in the rate of rise
Now, you note that the authors openly acknowledge that the rate of rise is measured in low-single-digit units of millimeters per year. So, why is the y-axis of Figure 2 measured in centimeters?
Hint: it’s because every point on that plot is a wild extrapolation.
This paper is not good, btw. The fact that it’s “only three pages” should be a blinking red sign telling you that it is not serious. Just read the more recent IPCC reports, because they deal with the question of updates from prior reports.
The plot you're citing is an imaginary projection 100 years into the future given what was known up to the year on the x-axis. That is why the units are 100x larger.
The uncertainty on the rate of change is quite large (relatively), therefore, any 100 year projection has huge, compounded uncertainty. Figure 2 is not useful for determining anything about the present.
No you can't. That study is comparing past estimates of the past and present to the lived in past and present not past estimates of the future to current estimates of the future.
Okay, but why then do the IPCC reports of the past present vastly different historical data than the present ones? History cannot change, but people can "reinterpret" it for political purposes.
Humans didn't exist since the beginning of time, and we only started to properly record temperatures in the last few centuries. That means we have to determine historical data through the effects it had on our planet. The methods to find this historical data from the effects keep changing and evolving, so it makes complete sense to me that historical data has changed throughout the reports.
Unfortunately you didn't specify where one can find this "vastly different historical data", so I can't get more specific than this.
https://iopscience.iop.org/article/10.1088/1748-9326/7/4/044...