> Here we account for the influence of three main natural variability factors: El Niño, volcanism, and solar variation.

All of these events are decades-long (or longer) cycles that don't have a substantial amount of data points... Sure, solar cycles seem to be 11 years, but we don't have a lot of scientifically usable (for forecasting) data points on that -- maybe 8 cycles? less? And the cycles are not consistent. It's not like Year 4 of one cycle is like year 4 of another cycle, we just determined there's a period of about 11 that looks significant.

Same with El Niño -- it's not like its 'true' or 'false', there's degrees of it.. and when it starts, and if other conditions are right to make additional hurricanes that year, and how much cloud cover that generates, etc. etc. a lot of which we don't have data on past 1960 when we launched our first weather satellite ...

As for volcanos... there's lots of them, and we are not great at predicting the high-impact events... we certainly don't have sufficient data to accurately predict what happens if we had a huge eruption on an El Niño strong year during the height of a solar cycle.

But if true presumably it’s one of the usual reasons for observing data with low likelihood according to a model: misspecification or statistical bias/variance.

https://en.wikipedia.org/wiki/All_models_are_wrong

When they say worst case, it means it’s possible. And only worst case within a percentage (like 95%) certainly, and based on known effects.

Worst cases are not some obligatory pessimism to scare people into accepting the mean probability case. They are serious warnings.

Given we are playing roulette with our planet’s climate stability, any major unaccounted for factors that reveal themselves are most likely to result in worse outcomes.

There have been people trying to bring attention to this sober information since the 80’s. Welcome to 2026. There will still be people complaining predictions are too dire.