GHCN’s Arctic Adjustments

By Paul Homewood

Before Adj After Adj

We have already seen that GHCN have been busy making large adjustments to the temperature records provided by the Icelandic Met Office. By cooling the past record up to about 1965 and/or increasing more recent temperatures, they have added about a degree of warming to the trend since the 1930’s at every Icelandic station. In doing so, they have flattened out the extremely cold spell in the 1960’s and 70’s, (well known in Iceland as the “Sea Ice Years”), and also done the same with the extremely warm period between 1930 and 1960. (Full story is here.)

It is important to recognise, though, that this climatic pattern was not simply a local effect limited to Iceland. HH Lamb, for instance, reports that in 1965 “sea temperatures around the Faroe Islands fell by 1.0C and were as cold as at any time in the previous 100 years.” (This series of sea temperatures is one of the longest in the world, dating back to 1867). Dickson and Osterhus, in their paper “100 Years In The Norwegian Sea”, find exactly the same pattern around Norway.

This is all borne out in the original temperature records for a wide range of Arctic stations that GISS still maintain, from GHCN V2, for instance Nuuk in Greenland below, or Ostrov Dikson in Siberia above.

Yet, just as in Iceland, the algorithm used by GHCN has decided that these climatic shifts never really occurred and adjusted them out of history. From Greenland, going east via Iceland and Norway, through to Siberia there are 21 GHCN stations above 64oN, which have current and long term records. In addition to the six Icelandic ones already reviewed, there are the following:-

Greenland

Nuuk

Angmagssalik

Norway

Jan Mayen

Bodo

Tromso

Vardo

Russia

Kandalaksa

Murmansk

Archangel

Kanin Nos

Ust Cilma

Malye Karmaku

Salehard

Ostrov Dikson

Dudinka

Of these 15 stations, the records remain unadjusted at six. The adjustments for the other nine are shown below.

As you will see, every station has had the same sort of adjustments as the Icelandic ones – either the past is cooled or the present is warmed, or both. Most stations have had adjustments of a degree or more.

GHCN have never provided any justification for these adjustments, and yet their effect is significant. The adjusted temperatures in GHCN V3.2 are used by GISS as the basis for their global temperature calculations. It is well known that neither GISS or GHCN have very little temperature data inside the Arctic Circle, as the map below shows. (This is based on 250km smoothing).

http://data.giss.nasa.gov/cgi-bin/gistemp/do_nmap.py?year_last=2012&month_last=9&sat=4&sst=1&type=anoms&mean_gen=1212&year1=2011&year2=2011&base1=1951&base2=1980&radius=250&pol=pol

And yet, by projecting temperature trends over 1200km, they manage to colour in the whole Arctic.

http://data.giss.nasa.gov/cgi-bin/gistemp/do_nmap.py?year_last=2012&month_last=9&sat=4&sst=1&type=anoms&mean_gen=1212&year1=2011&year2=2011&base1=1951&base2=1980&radius=1200&pol=pol

So it appears that adjustments at a small handful of stations can have a significant and disproportionate effect across the entire Arctic region, and in turn on GISS’s global temperature datasets.

Whatever the cause of these unjustified adjustments in the first place, it is the case that GHCN have known about this issue since February. Their failure to either remove or justify the adjustments suggests at the very least a degree of incompetence. Others may view this opinion as generous!

It has been suggested that I take the GHCN software codes apart to see what is wrong with them! If my car breaks down on the motorway with steam coming out of the bonnet, I don’t have to take the engine to bits to know it is buggered! On the contrary, it is up to GHCN to check their software, and either prove that it is working correctly or put right what is wrong with it.

It is also worth questioning the position of GISS in all of this. They too, to my personal knowledge, have been aware of these problems for many months. Their attitude has been to wash their hands and pass off the problem to GHCN. Although there may, of course, have been discussions behind the scenes, of which I have not been made aware, such an attitude raises questions about their own competence and scientific rigour.

We already know that satellite data shows less Arctic warming since 1979 than does GISS. One wonders what Jimmy Hansen’s map above would look like if we had had satellites back in 1940!

While such doubts remain about the GHCN V3.2 dataset, the GISS Surface Temperature Analysis becomes ever more suspect.

References

1) All unadjusted GHCN V2 temperatures are available at http://data.giss.nasa.gov/gistemp/station_data_v2/

2) The latest GHCN V3.2 temperatures can be accessed at http://data.giss.nasa.gov/gistemp/station_data/

3) GHCN before and after adjustments can be seen here ftp://ftp.ncdc.noaa.gov/pub/data/ghcn/v3/products/stnplots/ (Station numbers can be obtained from the GISS database).