"The indefatigable Anthony Watts, having noticed that the raw data for many individual stations in the GISS dataset had been "processed" so as to turn a century of actual cooling into a century of spurious warming, wondered whether the "processed" data itself had been altered over time with the aim of producing an ever-higher apparent (but bogus) rate of "global warming" over the 20th century. He found that this was indeed the case."