HadCRUT data begin in 1850, but are nearly worthless until about 1920, because there were so few weather stations, especially in the Southern Hemisphere.
The four honest HadCRUT charts show temperature changes in a way that reflects how those changes feel to a typical person -- very hard to notice.
Less than the typical temperature rise, in the first hour after sunrise, every day ... stretched over 100 years!
The two charts below showing the density of land weather stations on the globe are not specifically HadCRUT weather stations, but represent the poor land surface coverage before 1920.
You can't have accuracy with so few stations.
Ocean measurements were almost entirely in Northern Hemisphere shipping lanes, which is even worse global coverage.
I don't take global average temperature statistics seriously until 1979 when data from satellites became available as a check and balance to surface measurements.
Surface measurements still have poor coverage, and require a lot of guessing for areas with no weather stations, or with missing data.
Arbitrary "adjustments" that almost always create a faster global warming trend have been hard to believe over the past 50 years.
The inconvenient -0.5 to -0.6 degree C. cooling trend from 1940 to 1970, as reported in the mid-1970s, has been gradually "adjusted" away.
What remains today is between -0.1 degree C. cooling and no cooling at all.
That was obvious science fraud.
The bottom line: There has been global warming for 20,000 years, and for 325 years, and for the past 45 years. The exact amount is not known, and no Ph.D. degree can change that fact.
Some of the warming was accompanied by rising CO2 levels (warming in the past 45 years) and the rest can not be blamed on CO2.
We should be very happy about the warming in the past 325 years -- perhaps +2 degrees C., because it was too cold in the late 1600s.
There are three Central England weather stations with data since 1659, and their record is shown in the last two charts:
