One third of Arctic sea ice disappeared between 1890 and 1940, when CO2 levels were below 310 PPM.
Glaciers in Greenland and Norway were melting rapidly and facing “catastrophic collapse.”
The facts wreck global warming theory, so NASA quite predictably responded by erasing the 1940’s Arctic warmth.
According the the article above, peak ice thickness in 1940 was 218 cm. – which is considerably less than the current peak ice thickness.
There are many indications that the 1940’s were as warmer or warmer than the present, and that government climate scientists intentionally erased the warmth.
Global warming is not about science. It is about billions of dollars of government funding corrupting academia.