Did somebody alter historical records, or did climate trends suddenly deviate from historical trends?
I hate reporting that fails to state things clearly.
GISS was notified of an error in the program that assembles their temperature records for the U.S. and GISS went back and undid that particular mistake, resulting in different records for annual temperature averages.
As a side-answer, GISS modifies the historical records by some unknown process. This process is overseen by Hansen.