GHCN Adjusting The Adjustments

By Paul Homewood

I reported a couple of days ago that not only are GHCN making adjustments to historic temperatures that have been puzzling the national met offices, but that some of these adjustments have been changing almost on a monthly basis. These two towns in Argentina show this up well.

First, Santiago Del. Below are the GISS datasets for 11th April and today, following the April update.

The temperature for 1931 has been reduced by 0.59C , from 19.71 last week to 19.12 this week. This reduction has been applied up to 1969. (Last week’s version was actually the same as the actual temperature record, i.e. with no GHCN adjustments added.)

The second town is La Quiaca.

Here, the temperature for 1911 has increased from 6.74 to 8.34. Similarly all other temperatures to 1942 are increased by 1.6C (although this only has the effect of restoring the real temperature record, as previously the temperatures had been artificially adjusted down by an even larger amount).

According to Reto Ruedy at GISS

Looking at GHCN’s data for the first station (Santiago Del ..) and comparing it to the unadjusted data, I found that last month that record was not adjusted, this month it was adjusted – that seems to indicate that this station is according to GHCN’s criteria near the boundary of being exceptional and a single additional data point may have caused it to cross that boundary; I would not be too surprised if next month it would switch back to being unadjusted.

Either the original temperature record is right or it is not. If it is right, it should not be tampered with. If it can be proved to be wrong, and an appropriate adjustment can be justified, the adjustment should be made and then left alone.

Instead the GHCN/GISS temperature analysis is merely the construct of an algorithm, detached from reality.