I wish that all people writing about the climate would mention the questionable accuracy of global average temperature data before the use of weather satellite data in 1979, that acts as a "check and balance" on surface temperature numbers.
By "questionable", I mean the tiny claimed +/- 0.1 degree C. margins of error are not close to being believable.
Average sea temperature data are questionable before the use of ARGO floats in 2003.
All global average temperature data before World War II are a rough estimate, due to poor global coverage.
All global average temperature data before 1900 are close to wild guesses, due to very little Southern Hemisphere coverage, and they are not useful for real science.
There is enough evidence to prove the planet has warmed a lot in the past 20,000 years, and up to +2 degrees C. in the past 325 years. Trying to be more precise that that before 1979 is jumping to conclusions, IMHO.
The incomplete / infilled and repeatedly "adjusted" data from 1880 to World War II are NOT good enough for an accurate global average temperature.
Much more important than the low quality of global average temperature claims pre-World War II are:
(1)
The false claim that the climate can be predicted 100 years into the future,
(2)
The false claim that more CO2 in the atmosphere, and mild warming, is bad news and,
(3)
The bizarre claim that our inexpensive, reliable sources of electric power should be replaced, at great expense, with intermittent sources of power, requiring the greatest expansion of mining and manufacturing in human history.
And while the climate alarmists spend a huge amount of money on themselves, for a less reliable electric grid, about one billion people on our planet will continue to live without electricity.