One of the best sources for the land temperature record is the Historical Climatology Network (HCN). This is a record produced by thousands of individuals all across the globe that visit meteorological weather stations each and every day and dutifully record the min and max temperatures, along with precipitation levels. And they have been doing this for over a 100 years. To my way of thinking, this is the definitive source for the global temperature record. The USHCN is just a subset which only includes stations for the US. You can start your research into the USHCN at the following location.
I get my data by visiting their FTP site at the following location.
Here is a graph produced by taking the data, calculating the average TMAX for all the stations and turning it into a time series. This graph is the official temperature statement published by NOAA.
There is one problem with that graph though. It is the “FINAL” result after tampering with the data. You can find several versions of the data on their site because these data adjustments have gone through several iterations in the last 20 years. Setting aside the reasoning behind the adjustments for now, I want to first address what they have done and what was the result. So, here is a result of the original data before any adjustments were made to it. Totally different message.
If you subtract the original raw measurements from the final, or adjusted measurements you can derive the temperature offset that was applied to the data. If you now plot that against the year, you get the following graph. The results of adjusting the data, have cooled much of the past by 1.5 and warmed recent records by a degree. That is fully 2.5F. Sound familiar?
Now, if you then map that data against the co2 levels for those years, you get this graph. The adjustments, map very nicely to the growth of CO2. How is that for making the data fit the narrative?
Another confirmation. So here is a graph that Nasa released back in 1999. 1998 was hot but not nearly as hot as 1934 and pretty much a cooling trend from 1934-1998.
Now here is the same date range that Nasa has recently released, 20 years later. Compare what has happened to 1934 and 1998 in both graphs.
Nasa takes data from the GHCN and adjusts it to produce the GISS. This has gone through a number of iterations and they are currently at GISTEMP V4 (as of fall 2019)
Here is another look at what Nasa has done to the temperature record since 2000.