Why there is no reason for you to trust the official global temperature records

The officially published global temperature records all converge on a total temperature rise since the late 19th century of about 0.9 (0.8–1.0) degrees Celsius:

Figure 1.

But to what extent can we be confident that this is how the ‘global average surface temperature’ (GAST) anomaly actually evolved over this time frame?

The truth is: We can’t. At all.

This is fundamentally a matter of data coverage, but – just as importantly – it is also a matter of methodology. How do you make up for a paucity of data? How do you properly compile, weight and interpolate data into a reliable “global average” when that data – the actual observational information that you have collected and thus have at your disposal – provides nothing like a full global coverage? And how do you make this “global average” of yours consistent over time when your data coverage (both in total and in spatial distribution) vastly changes over that same time frame? What basic assumptions will you have to rely on? Because, make no mistake, an interpretive undertaking such as this will crucially have to rest on a foundation of some rather sweeping presuppositions. Continue reading


The ship-buoy bias correction excuse (HadSST3 and ERSSTv4)

In 2011, the Hadley Centre of the UK Met Office replaced their global sea surface temperature series, HadSST2, with a new one, HadSST3, an upgrade allegedly necessitated by, among other things, the particular ‘discovery’ that the recorded temperature evolution of the global ocean surface had, since about 1979, for one particular reason followed a path that trended artificially low. The official global sea surface temperature data as compiled simply showed too little overall warming. Since 1978-79, that is, during the satellite era.

This is funny, because the Hadley Centre’s own official global SST dataset, HadSST2, already showed an overall warming since the late 70s that was much larger than the other official datasets out there, like ERSST, Reynolds OI and HadISST:

Animation 1.

Note that the new ERSSTv4 series is also included in Anim.1 (red curve), and that it distinctly supports the group of ‘others’: The light blue HadSST2 curve all of a sudden makes a giant upward leap of nearly 0.1K at the 1997-1998 transition (light green vertical line). There is hardly any divergence to be observed between it and the others, however, either before or after this point (save that from ERSSTv4 post 2005; more on that later …). Continue reading