Is there a Homogenisation Bias in Paraguay’s Temperature Data?

Last month Paul Homewood at Notalotofpeopleknowthat looked at the temperature data for Paraguay. His original aim was to explain the GISS claims of 2014 being the hottest year.

One of the regions that has contributed to GISS’ “hottest ever year” is South America, particularly Brazil, Paraguay and the northern part of Argentina. In reality, much of this is fabricated, as they have no stations anywhere near much of this area…

….there does appear to be a warm patch covering Paraguay and its close environs. However, when we look more closely, we find things are not quite as they seem.

In “Massive Tampering With Temperatures In South America“, Homewood looked at the “three genuinely rural stations in Paraguay that are currently operating – Puerto Casado, Mariscal and San Juan.” A few days later in “All Of Paraguay’s Temperature Record Has Been Tampered With“, he looked at remaining six stations.

After identifying that all of the three rural stations currently operational in Paraguay had had huge warming adjustments made to their data since the 1950’s, I tended to assume that they had been homogenised against some of the nearby urban stations. Ones like Asuncion Airport, which shows steady warming since the mid 20thC. When I went back to check the raw data, it turns out all of the urban sites had been tampered with in just the same way as the rural ones.

What Homewood does not do is to check the data behind the graphs, to quantify the extent of the adjustment. This is the aim of the current post.

Warning – This post includes a lot of graphs to explain how I obtained my results.

Homewood uses comparisons of two graphs, which he helpful provides the links to. The raw GHCN data + UHSHCN corrections is available here up until 2011 only. The current after GISS homogeneity adjustment data is available here.

For all nine data sets that I downloaded both the raw and homogenised data. By simple subtraction I found the differences. In any one year, they are mostly the same for each month. But for clarity I selected a single month – October – the month of my wife’s birthday.

For the Encarnacion (27.3 S,55.8 W) data sets the adjustments are as follows.

In 1967 the adjustment was -1.3C, in 1968 +0.1C. There is cooling of the past.

The average adjustments for all nine data sets is as follows.

This pattern is broadly consistent across all data sets. These are the maximum and minimum adjustments.

However, this issue is clouded by the special adjustments required for the Pedro Juan CA data set. The raw data set has been patched from four separate files,

Removing does not affect the average picture.

But does affect the maximum and minimum adjustments. This is shows the consistency in the adjustment pattern.

The data sets are incomplete. Before 1941 there is only one data set – Ascuncion Aero. The count for October each year is as follows.

In recent years there are huge gaps in the data, but for the late 1960s when the massive switch in adjustments took place, there are six or seven pairs of raw and adjusted data.

Paul Homewood’s allegation that the past has been cooled is confirmed. However, it does not give a full understanding of the impact on the reported data. To assist, for the full year mean data, I have created temperature anomalies based on the average anomaly in that year.

The raw data shows a significant cooling of up to 1oC in the late 1960s. If anything there has been over-compensation in the adjustments. Since 1970, any warming in the adjusted data has been through further adjustments.

Is this evidence of a conspiracy to “hide a decline” in Paraguayan temperatures? I think not. My alternative hypothesis is that this decline, consistent over a number of thermometers is unexpected. Anybody looking at just one of these data sets recently, would assume that the step change in 40-year-old data from a distant third world country is bound to be incorrect. (Shub has a valid point) That change goes against the known warming trend for over a century from the global temperature data sets and the near stationary temperatures from 1950-1975. More importantly cooling goes against the “known” major driver of temperature recent change – rises in greenhouse gas levels. Do you trust some likely ropey instrument data, or trust your accumulated knowledge of the world? The clear answer is that the instruments are wrong. Homogenisation is then not to local instruments in the surrounding areas, but to the established expert wisdom of the world. The consequent adjustment cools past temperatures by one degree. The twentieth century warming is enhanced as a consequence of not believing what the instruments are telling you. The problem is that this step change is replicated over a number of stations. Paul Homewood had shown that it probably extends into Bolivia as well.

But what happens if the converse happens? What if there is a step rise in some ropey data set from the 1970s and 1980s? This might be large, but not inconsitent with what is known about the world. It is unlikely to be adjusted downwards. So if there have been local or regional step changes in average temperature over time both up and down, the impact will be to increase the rate of warming if the data analysts believe that the world is warming and human beings are the cause of it.

Further analysis is required to determine the extent of the problem – but not from this unpaid blogger giving up my weekends and evenings.

Kevin Marshall

All first time comments are moderated. Please also use the comments as a point of contact, stating clearly that this is the case and I will not click the publish button, subject to it not being abusive. I welcome other points of view, though may give a robust answer.

AndThenTheresPhysics on Paraguayan Temperature Data

The blog andthentheresphysics is a particularly dogmatic and extremist website. Most of the time it provides extremely partisan opinion pieces on climate science, but last week the anonymous blogger had a post “Puerto Casado” concerning an article in the Telegraph about Paraguayan temperature by Christopher Booker. I posted the following comment

The post only looks at one station in isolation, and does not reference original source of the claims.

Paul Homewood at notalotofpeopleknowthat looked at all three available rural stations in Paraguay. The data from Mariscal and San Jan Buatista/Misiones had the same pattern of homogenization adjustments as Puerto Casado. That is, cooling of the past, so that instead of the raw data showing the 1960s being warmer than today, it was cooler.

Using his accountancy mind set, Homewood then (after Booker’s article was published) checked the six available urban sites in Paraguay. His conclusion was that

warming adjustments have taken place at every single, currently operational site in Paraguay.

Then he looked at all 14 available stations in neighbouring Bolivia. His conclusion

At every station, bar one, we find the ….. past is cooled and the present warmed.”

(The exception was La Paz, where the cooling trend in the raw data had been reduced.)

Homogenization of data means correcting for biases. For a 580,000 sq mile area of Central South America it would appears strong adjustment biases to have been introduced in a single direction.

Homewood references every single site. Anyone can easily debunk my summary by searching the following:-

Jan-20 Massive Tampering With Temperatures In South America

Jan-26 All Of Paraguay’s Temperature Record Has Been Tampered With

Jan-30 Cooling The Past In Bolivia

My comment did not contain the hyperlinks or italics. It has been deleted without passing through moderation. The only bit of the moderation policy I believe that I fall foul of is the last.

This blog is also turning out to be both more time consuming and more stressful than anticipated. Some moderation may be based purely on whether or not I/we can face dealing with how a particular comment thread is evolving. This is not a public service and so, in general, any moderation decision is final.

The counter-argument from ATTP is

If you look again at the information for this station the trend before adjustments was -1.37oC per century, after quality control it was -0.89 oC per century, and after adjusting for the station moves was +1.36 oC per century. Also, if you consider the same region for the same months, the trend is +1.37 oC per century, and for the country for the same months it is +1.28 oC per century. So, not only can one justify the adjustments, the result of the adjustments is consistent with what would be expected for that region and for the country.

Paul Homewood has investigated all the other stations in Paraguay or in neighbouring Bolivia and found similar ad hoc adjustments. It completely undermines ATTP’s arguments. This anonymous individual is wrong. Rather than face dealing that he is wrong, ATTP has deleted my comment. He is entitled to his beliefs, and in a free society can proselytize to his heart’s content. But there are boundaries. One of them is in suppressing evidence that undermines the justification for costly and harmful public policies. That is policies that are harming the poor here in Britain, but (and more importantly) can only be remotely successful by destroying the prospect of increasing living standards for over half the world’s population. Paul Homewood and others are increasingly uncovering similar biases in the temperature record in other parts of the world. The underlying data for the global surface temperature sets is in need of a proper, independent audit, to determine the extent of the biases within it. But when the accusation that the Paraguayan temperature data set is corrupted, people will point to ATTP’s blog post as evidence that there is but a single instance, and that instance has been debunked. Another boundary is a value that that many in the criminal justice system also hold dear. The more emotive the subject, the greater all concerned must go out of their way to compare and contrast the arguments. That way, the influence of our very human prejudices will be minimized. Again, independent audits will help eliminate this. If ATTP thinks he has all the answers then he will not be afraid to encourage people to look at both sides, evaluate by independent standards, and make up their own minds.

Kevin Marshall

Comment ATTP 310115

Instances of biases in the temperature sets

This will be added to when I get time.

Paul Homewood on San Diego data 30-01-15

Shub Niggareth looks into the Puerto Casado story 29-01-15

Paul Homewood on Reykjavik, Iceland 30-01-15

Jennifer Marohasy letter on Australian data 15-01-15

Update 01-02-15

I have invited a response from ATTP, by posting #comment-46021.


You have deleted two of my comments in the last 24 hours that meet all of your moderation criteria except one – that you cannot face dealing with a challenge. That is your prerogative. However, the first comment, (now posted on my blog) I believe completely undermines your argument. Paul Homewood has shown that the Puerto Casado dataset homogenization did not make it consistent with neighbouring non-homogenized surface temperature stations, but that all the Paraguayan and neighbouring Bolivian surface temperature stations were “homogenized” in the same way. That is, rather than eliminating the biases that local factors can create, the homogenizations, by people far removed from the local situations, effectively corrupted the data set, in a way that fits reality to the data.

I might be wrong in this. But based on your arguments so far I believe that my analysis is better than yours. I also believe that who has the better argument will only be resolved by an independent audit of the adjustments. If you are on the side of truth you would welcome that, just as a prosecutor would welcome the chance to prove their case in court, or a pharmaceutical company would welcome independent testing of their new wonder-drug that could save millions of lives. Even if I am wrong, I will be glad at being refuted by superior arguments, as I will know that to refute my claims will require you to up your game. Humanity will be served by my challenging a weak case and making it stronger. You have generated over 500 comments to your post, so an appeal for help via email should generate some response. If that does not work there are many well-funded organisations that I am sure will rush to your assistance.

There are at least seven options I think you can take.

  1. Ignore me, and pretend nothing has happened. Bad idea. I will start analysing your posts, as you did with Wattsupwiththat, only rather than your pea-shooters firing blanks, I have the heavy artillery with HE shells.
  2. Do an attack post – like desmogblog or Bob Ward of the Grantham Institute might do. Bad idea, I will take that as perverting or suppressing the evidence, and things will get rather rough. After all, I am but a (slightly) manic ex-beancounter, and you have the consensus of science on your side, so why is should sending in the PR thugs be necessary unless you are on the losing side?
  3. Get together a response that genuinely ups the game. Win or lose you will have served humanity as I and others will have to rebut you. Engage and all will gain through greater understanding.
  4. Admit that there are other valid points of view. A start would be to release this comment, which will get posted on my blog anyway. I quite accept that you cannot come up with a rebuttal at the drop-of-a-hat. A simple comment that a response will be made sometime this year is fine by me.
  5. Also call for a truly independent audit of the surface temperature set. It could be for your own reasons, and if truly independent, I will support it. If a whitewash, like the enquiries that Gordon Brown ordered into Climategate, an audit will do more harm than good.
  6. Close down your blog and do something else instead. You choose to be anonymous, and I respect that. Walking away is easy.
  7. Admit that you got this one wrong. You will take some flack, but not from me.