How Temperature Adjustments Have Transformed Arctic Climate History

By Paul Homewood

 

There seems to have been a campaign of misinformation, to downplay the significance of the Arctic temperature adjustments we have been looking at.

 

The claim is that they make little difference to temperature trends there, so let’s test this out with the example of Akureyri.

 

 

 ftp://ftp.ncdc.noaa.gov/pub/data/ghcn/v3/products/stnplots/6/62004063000.gif

Note that the temperatures were cooled from 1922 to 1965, effectively in the middle of the record, which started in 1882. As a result the overall trend since 1882 has remained virtually the same. But, of course, this is not the point, as it is the trend since the 1920’s that is significant.

We can see the effect on trends, using 5-year running averages in the chart below.

 

 

http://data.giss.nasa.gov/tmp/gistemp/STATIONS/tmp_620040630003_1_0/station.txt

http://data.giss.nasa.gov/tmp/gistemp/STATIONS/tmp_620040630000_12_0/station.txt

 

The original data shows that the period from 1930 to about 1950 was every bit as warm as the last decade. (Raw and adjusted data has been the same since 1990).  There is also a clearly evident cycle.

After adjustments, there is just a steadily increasing trend, albeit with a flattish interval in the middle.

Although there were some adjustments made in 1948, an adjustment of 1.08C was made in 1966, effectively reducing previous temperatures. This was in reaction to a sharp fall in temperatures over the previous two years, from 4.70C to 2.18C, which the algorithm assumed was due to changes in observation practices.

When we check around the region, however, we find that there were similar temperature drops all over the place. I offer a few examples below, but, as we have seen, similar adjustments were made at nearly every station in that part of the Arctic at around that time.

 

	1964	1966	Diff
Angmassalik, Greenland	-0.28	-2.29	-2.01
Stykkisholmur, Iceland	5.05	3.10	-1.95
Reykjavik, Iceland	6.04	4.24	-1.80
Jan Mayen, Norway	-1.29	-2.48	-1.19
Archangel, Russia	1.07	-1.07	-2.14
Murmansk, Russia	0.58	-2.47	-3.05

 

 

It is worth noting what the Iceland Met Office have to say about the sea ice years:

 

A comparison of annual temperatures at three stations, Stykkishólmur in the west, Akureyri in the north and Reykjavík in the southwest reveals some inter-station differences.

The first cold interval, the "ice years", was the coldest of the three in the north and east, but the 1979 to 1986 was the coldest in southwestern Iceland.

 

This would explain why the temperature drop at Akureyri was greater than the other two.

One other thing worth pointing out is the timing of the onset of cold. In Nuuk, which unlike Angmassalik, lies on the west side of Greenland, the cold came a year later, with the temperature dropping by 2.28C between 1965 and 1967.

Over in Siberia, however, the cold came earlier. For instance, there was a drop of 4.51C between 1962 and 1964. Other stations such as Salehard and Ust cil Ma experienced similar drops.

Certainly, this different timing may have confused the algorithm.

 

It is ludicrous to assume that all of these drops in temperature were due to station moves or equipment changes.

But we don’t have to make assumptions at all, as there is overwhelming evidence of this dramatic climatic shift. For instance, Dickson & Overhus:

 

The East Icelandic Current, which had been an ice-free Arctic current in 1948-1963, became a polar current in 1965-1971, transporting drift ice and preserving it…..

Aided by active ice formation in these polar conditions, the Oceanic Polar Front spread far to the south-east of normal, with sea ice extending to the north and east coasts of Iceland….

However, the Great Salinity Anomaly is certainly one of the most dramatic events of the century in the Norwegian Sea.

 

Or, Lawrence Hamilton, Sea Changes Ashore: The Ocean and Iceland’s Herring Capital:

 

In the mid-1960s, northwesterly winds associated with a prolonged negative NAO/AO state drove unusual volumes of polar surface water and ice through Fram Strait into the Greenland and Iceland seas.

Dickson et al. (1988:103) described this as “one of the most persistent and extreme variations in global ocean climate yet observed in this century.”…

From 1920 until 1965, relatively warm conditions prevailed over the northern North Atlantic. In 1965, a sudden change occurred; drift ice and polar water covered the north Icelandic shelf during spring.

  

And then there is HH Lamb, “Climate, History & The Modern World”:

 

A greatly increased flow of the cold East Greenland Current has in several years (especially 1968 and 1969, but also 1965, 1975 and 1979) brought more Arctic sea ice to the coasts of Iceland than for fifty years. In April-May 1968 and 1969, the island was half surrounded by ice, as had not occurred since 1888.

 

 

Let us recall that the GHCN adjustments are triggered by “an abrupt shift in temperature”. There was indeed such an abrupt shift in the 1960’s, and it was real.

 

 

Final Thoughts

A few further thoughts:

 

1) Whenever I raise the question of temperature adjustments, some nonentity usually jumps up and down and tells me to check the algorithm and work out how the adjustments were calculated.

I have no intention of doing so. The adjustments have been made by GHCN, and it is up to them to explain and justify, which is precisely what I have been asking them to do on numerous occasions, without response.

Can I make it clear then that I do not intend to get into any more debate with anybody who thinks they have the right to tell what I should or should not be doing. Any such comments will in future go straight into the spam box.

 

2) All warming and cooling adjustments balance out.

This is a common defence, but I fail to see the relevance. If incorrect warming adjustments are cancelled out by incorrect cooling ones, then we appear to have twice as many errors.

This hardly gives much confidence in the “robustness” of the global temperature datasets.

If, on the other hand, the cooling adjustments are correct, then clearly global warming has been overstated.

All I can say to those who put forward the “cooling adjustments” defence is to contact GHCN if they feel they are incorrect.

 

3) Accusations have been made that it is being “unscientific” to object to adjustments, as there may be good reasons for them.

My reply is that it is certainly not scientific to defend such adjustments, unless you can offer concrete evidence for them. And it is definitely “unscientific” to defend them, when real world scientific evidence contradicts them.

 

4) Some have suggested that we should simply trust the algorithms, and that we should let the “scientists” carry on with their work, as they must know best.

In other words, any evidence which suggests they may be wrong should be suppressed (unless, of course, you write a pal reviewed paper and get it past their gate keepers).

I find this view astonishing. Scientists, particularly public funded ones, should always be held accountable for their work. And any legitimate concerns must be addressed in an open and transparent manner.

The idea that these concerns should be hidden away from the public is abhorrent.