What is "hadcrut"

HadCRUT is the dataset of monthly instrumental temperature records formed by combining the sea surface temperature records compiled by the Hadley Centre of the UK Met Office and the land surface air temperature records compiled by the Climatic Research Unit (CRU) of the University of East Anglia.

The data is provided on a grid of boxes covering the globe, with values provided for only those boxes containing temperature observations in a particular month and year. Interpolation is not applied to infill missing values. The first version of HadCRUT initially spanned the period 1881–1993, and this was later extended to begin in 1850 and to be regularly updated to the current year/month in near real-time.