The earliest monthly global dataset that we have available from NASA is the one produced for the August 2005 reporting period. Overall, that dataset contains 1,508 monthly observations since the beginning of 1880.
It seems that under Obama, NASA has conducted a global warming fabrications corrections effort, especially focused on the most recent decades since the 1970's.
Specifically, when comparing the newly adjusted NASA dataset to the one reported in August 2005, out of the 308 months spanning January 1980 through August 2005, NASA has warmed 302 months (only 2 months were cooled and 6 were left unchanged from the 2005 dataset).
Of the total warming adjustments corrections applied to the 1980's, 1990's and 2000's (through Aug 2005) they average out to a bureaucrat-made warming increase of +0.08°C per month.....
===> that's equal to a 96°C per century warming trend if NASA continues with a pattern of similar "corrections."
This NASA non-random treatment and purposeful changes of past empirical evidence is beyond just being anti-science. It is fraud-like, with the root cause being attempts by bureaucrat-scientists to meet the political and propaganda agendas of government elites - agendas that have been blatantly obvious over recent years.
Prior to the upcoming, yawn-producing UN's 2015 Paris COP21 greenhouse gas fear-mongering conference, one could surmise that NASA was charged with creating global temperatures that were the hottest ever, regardless of the integrity and credibility damage that the science community and objective scientific methodologies would sustain.
NASA provides ample evidence why scientists, bureaucrats and political elites should be held in contempt by the public. Literally, their utterances should never be trusted on any issue that requires an objective, impartial scientific treatment.
'Never trust, only verify' should be the new motto for the public to take to heart.
Note: Spreadsheet with NASA GISS datasets: August 2005 & June 2015