Government agencies in charge of keeping historic temperature records claim they occasionally “adjust” the temperature records to fix problems with bad thermometers, etc.
For example, NOAA officials will point to places where a thermometer system was malfunctioning. They will then claim that the official records of past years have been “adjusted” to fix the problem.
But data analyst Tony Heller has shown that the “adjustments” have tended to make the past colder and the present warmer. “In the case of US temperature adjustments, they are made to exactly match the increase in CO2. Junk science doesn’t get any worse than that.“