Models say only what the modeler tells them to say.
It also has been and continues to be tremendously accurate and predictive.
I am unable to find any 1982 Exxon prediction that would meander like the line in that graph. The only plot I was able to find is this [1] from this 1982 Exxon report [2], which is just a slightly curved upward rising sketch, not nearly as detailed as in the xkcd graph.
> the Exxon model from 1982
I also failed to find any signs of there having been any "1982 Exxon model". What [2] is, is a 39-page report, a synthesis and review of publicly available climate research. The list of references is quite extensive: 10 pages.
[1] https://pbs.twimg.com/media/D6fbaqdWwAEPg5Z.png
[2] https://www.climatefiles.com/exxonmobil/1982-memo-to-exxon-m...
For all of us, myself included.
That said, even highly adversarial climate models greated almost half a century ago have tremendous predictive power.
Large systems are modelable. Not with any degree of precision, of course, but a high degree of accuracy.
Otherwise insurance companies wouldn’t exist.
Yes. About the warming effect of doubling the atmospheric CO2 (Equilibrium Climate Sensitivity):
Manabe and Wetherald 1967, said 2.3°C.
The Charney Report 1979, said 3.0 ± 1.5°C.
IPCC AR6 2021, says 3.0°C (2.5 to 4.0).
https://journals.ametsoc.org/view/journals/atsc/24/3/1520-04...
https://www.bnl.gov/envsci/schwartz/charney_report1979.pdf
https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6...
It's the very definition of how computer models work. The modeler writes the program, determines all the inputs, determines how the logic of the program will respond to the inputs, etc. The modeler is in complete control of the model, tells it how to behave, and thus the model says only what the modeler tells it to.
> Are you implying that climate change isn't happening?
Non sequitur.
Offhandedly portraying scientists and researchers as dishonest and conspirators in every opportunity possible seems the default here.
https://journals.ametsoc.org/view/journals/bams/98/3/bams-d-...
They test these models with other planets too. Set in parameters for Mars or Venus and they precinct pretty well how those climates behave.
This is also done in weather forecasting, though maybe they run the model in reverse, I can't recall. Same idea though, verify with existing data before predicting.
> The question of whether the twentieth-century warming should be considered a target of model development or an emergent property is polarizing the climate modeling community, with 35% of modelers stating that twentieth-century warming was rated very important to decisive, whereas 30% would not consider it at all during development. Some view the temperature record as an independent evaluation dataset not to be used, while others view it as a valuable observational constraint on the model development. Likewise, opinions diverge as to which measures, either forcing or ECS, are legitimate means for improving the model match to observed warming. The question of developing toward the twentieth-century warming therefore is an area of vigorous debate within the community.
And do I read it right that 35% of scientists deem it important that a model indicates future warming? Science doesn’t work that way, you don’t get to choose a conclusion then model for it.
No, you read it wrong. 35% thinks it appropriate to fit to past warming. Of course nobody is suggesting to fit to future warming! But past warming is observed.
If you are familiar with training/test split in machine learning, some thinks past warming is in training set (and test with things like reproducing ENSO), and some thinks past warming is in test set. I think it boils down to disagreement over how determined was twentieth-century warming.