NASA publishes maps and graphs like these ones, purporting to show very detailed trends in global temperature back to 1880, with very small error bars. Their maps are based on NOAA GHCN data.
Then NASA claims that multiple data sets agree very closely.
It all looks so convincing, until you look at the actual data. The maps below show the locations of all NOAA GHCN stations which had daily min/max temperature data in the year 1900. As you can see, the US had very good coverage, and the rest of the world had almost no coverage.
They have no idea what temperatures outside the US were in the year 1900. The global temperature record from NOAA/NASA/CRU/JMA is a complete fake, and the only reason that they come up with the same graph is because they are colluding to defraud the public.
The only place which has good data back to 1900 is the US, and NOAA massively tampers with the US data to cool the past and create fake warming.
This is the biggest scam in history. Global warming is a complete fake.