It would be interesting to look into whether they had good reasons for thinking this at the time.
Henry's Law? Correct me if I'm wrong, but the oceans hold something like 98% of the CO2 in the biosphere, so it's easy to predict that in equilibrium they'll absorb something like 98% of the fossil carbon we add to the biosphere. It might not have been as easy to predict the transient behavior; IIRC the oceans are only absorbing CO2 at roughly a third of the rate at which we're now emitting it, just because the mixing processes are so slow.
Thanks.
In Intelligence Explosion analysis draft: introduction, Luke Muehlhauser and Anna Salamon wrote
As a part of the project "Can we know what to do about AI?", I've summarized my initial impressions of Arrhenius's predictions and the impact that they might have had. The object level material is all draw from Wikipedia, and I have not vetted it.
Taking this all together, based on my surface impressions, I think that this case study gives evidence against attempting to predict the far future being useful: