The global "warming" charade is not about saving humanity, nor about saving polar bears...it's all about a non-environmental agenda that is being pursued by the establishment elites and powerful...and they aren't bashful about admitting it...thus, government agencies, such as NOAA, will fabricate anything and everything in support of the agenda.....
The global warming political agenda requires proof that temperatures are getting hotter.
If "hotter," then the public will of course need the government to step in and save them from dangerous hot temperatures.
But what happens when the modern maximum temperatures do not fit the agenda by not being as hot as those experienced in the distant past, earlier in the 20th century?
Well, in the case of NOAA, they just fabricate the "proof."
How?
By simply lowering adjusting past annual maximum U.S. temperatures down until they are below the modern era temps; plus, to provide a little oomph, they raise the modern maximums a bit.
As this chart reveals, NOAA massively lowered the past temperatures prior to the 1990's. The broad black curve is the 5-year mean of the maximum U.S monthly temperatures originally measured and recorded.
And the broad blue curve? That's the 5-year mean of maximum temperatures after NOAA finished with their fabrications adjustments.
Figuratively, with a few strokes of the keyboard, NOAA manipulated the long-standing historical climate records in order to present needed "evidence" that fits with the political agenda.
Unfortunately for the reputation and credibility of science, this style of empirical evidence falsification is widespread, with government climate "scientists" leading the way it would appear.
Note: Original source of chart; the animated gif image was separated into its two frames using '7GIF.' The colors of the the two frames were then changed to be different. Then one graph was superimposed on another.