You are correct, it couldn't and in fact 1850 has traditionally been referred to in climatology as "pre industrial", but this site is really the wrong place to try and actually talk about science. The intellectual curiosity fans here don't like it at all.
Thank you - I was surprised by the down votes, although I could have added more detail to make my objection even more clear, e.g:
Using the Stefan Boltzmann law, 1 extra degree corresponds to about an extra 3 W/m2 of greenhouse radiation (using an emissivity of 0.6 for the atmosphere.) To raise 1 m2, 1 cm thick water (10 kg) by 1 C would require (4 J/g/K)*(10,000 g) ~ 40,000 J, or about 4 hours. So 100 m would take 4 years, 3 km (the average depth of the ocean) ~100 years, assuming perfect mixing. So the ocean temperature would lag by decades, possibly centuries, even if the atmosphere ramped up by 1 degree from 1850-1900, which it didn't.
