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The uncertainty of science: An analysis of the surface global weather data, dubbed GHCN and used by NASA’s Goddard Institute of Space Sciences (GISS) to demonstrate the climate has been warming for the past century, has found that 66% of that data is adjusted or estimated and is not based on the actual raw data.
Overall, from 1880 to the present, approximately 66% of the temperature data in the adjusted GHCN temperature data consists of estimated values produced by adjustment models, while 34% of the data are raw values retained from direct measurements. The rural split is 60% estimated, 40% retained. The non-rural split is 68% estimated, 32% retained. Total non-rural measurements outpace rural measurements by a factor of 3x.
The estimates produced by NOAA for the GHNC data introduce a warming trend of approximately a quarter degree C per century. Those estimates are produced at a slightly higher rate for non-rural stations than rural stations over most of the record. During the first 60 years of the record measurements were estimated at a rate of about 75%, with the rate gradually dropping to 40% in the early 1990s, followed by a brief spike in the rate before resuming the drop to its present level.
Approximately 7% of the raw data is discarded. If this data were included as-is in the final record it would likely introduce a warming component from 1880 to 1950, followed by a cooling component from 1951 to the present.
As I have noted previously, all the adjustments cool the past and warm the present, a pattern that is just not realistic in the real world, and could only exist if the people doing the adjustment are either not recognizing their biases or are consciously manipulating the data to prove those biases.
Either way, the surface temperature data as released by GISS is simply not trustworthy for determining the changes in the Earth’s climate over the past few centuries.