A total sham:
"When future generations look back on the global-warming scare of the past 30 years, nothing will shock them more than the extent to which the official temperature records – on which the entire panic ultimately rested – were systematically “adjusted” to show the Earth as having warmed much more than the actual data justified....
Of much more serious significance, however, is the way this wholesale manipulation of the official temperature record – for reasons GHCN and Giss have never plausibly explained – has become the real elephant in the room of the greatest and most costly scare the world has known. This really does begin to look like one of the greatest scientific scandals of all time."
The fiddling with temperature data is the biggest science scandal ever - Telegraph