HADCRUT Global Temperature Anomaly (part 1)

A quick squizz at the latest data with a side order of cogitation.

The HADCRUT global temperature anomaly combines the CRUTEM5 land surface air temperature and HADSST4 sea surface temperature anomaly data series in order to get some idea of what the world is doing. Details on this stalwart effort by us Brits may be found here. NOAA does similar, as does Berkeley (BEST), ECMWF (ERA5) and NASA (GISS). The work involved in deriving these time series from raw data is mind-boggling; neither should we underestimate the amount of adjustment, estimation, modelling and infill that takes place.

A member of the public looking at these magnificent time series can be forgiven into thinking they are looking at real world observations made over time. Certainly, a real temperature measurement at some place at some time gets the ball rolling, but these individual location measurements are then subject to a great deal of processing and come with a stupendous amount of bias. I’ll be taking at closer look at this in future newsletters

All of these major data players use t…