James Hansen is one of the world's most active MMGW alarmists. He personally controls the GISS data set, which is, oddly enough, the one that shows the greatest amount of global warming, often when other sets show no warming or even cooling. Via Bishop Hill, this bit of speculative statistical analysis:
One of the main sources of global warming information, the GISS data set from NASA showed significant management*, particularly a deficiency of zeros and ones.* Or "fiddling" to you and me.