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>Hostile witnesses on Climategate

2009 December 12 Leave a comment

> Much of the internet was abuzz about the released emails and documents from the Climate Research Unit at the University of East Anglia, now referred to as Climategate (or the CRUtape letters). Notable for their silence were more mainstream newspapers and internet news sites. And when Climategate was covered the issue was minimised as having no real significance, a normal spat between fallible people who happened to be scientists, and having no bearing on the truth of anthropogenic global warming.

I think it does have bearing because if the scientists involved are shown to be otherwise dishonest, there is reason to suspect this character flaw would extend to fraudulent reporting and publishing in the scientific arena.

The desire and willingness for fellow global warming affirmers to defend these people is slightly concerning. Appropriate responses are to withhold judgment until further information is available, or to decry such behaviour as damaging to the issue. Dubious defence for one’s cause should be shunned, it causes damage in the long run.

Several who are convinced of the reality of global warming have realised the serious nature of these emails and stated as such. Below are several links to comments by people who otherwise think global warming is real and man-made. I do not agree with this hypothesis, nor everything they have written in these articles. I include them to emphasise to those who subscribe to global warming that the emails and documents are of a serious nature and suggest dodgy behaviour by several people in the forefront of the pro-global warming debate.

George Monbiot

There appears to be evidence here of attempts to prevent scientific data from being released, and even to destroy material that was subject to a freedom of information request.Worse still, some of the emails suggest efforts to prevent the publication of work by climate sceptics, or to keep it out of a report by the Intergovernmental Panel on Climate Change. I believe that the head of the unit, Phil Jones, should now resign. Some of the data discussed in the emails should be re-analysed.

Chip Knappenberger

As it now stands, a bias can exist in the current system. That it does exist is evident in the Climategate emails. By all appearances, it seems that some scientists are interested in keeping certain research (and particular researchers) out of the peer-review literature (and national and international assessments derived there from). While undoubtedly these scientists feel that they are acting in the best interest of science by trying to prevent too much backsliding and thereby keeping things moving forward efficiently, the way that they are apparently going about it is far from acceptable.

Instead of improving the process, it has nearly destroyed it.

If the practitioners of peer-review begin to act like members of an exclusive club controlling who and what gets published, the risk is run that the true course of science gets sidetracked. Even folks with the best intentions can be wrong.

Richard Tol

The emails reveal a systematic effort to deny legitimate freedom-of-information requests.

They contain evidence that the rules of the UN’s Intergovernmental Panel on Climate Change were deliberately broken to include a paper that supports a particular point of view.

The emails show an intolerance of views and facts that do not support the received wisdom of the people involved.

One of the stolen documents reveals that a key result, the instrumental record of the global mean temperature since 1850, cannot be reproduced.

This is serious stuff.

John Tierney

As the scientists denigrate their critics in the e-mail messages, they seem oblivious to one of the greatest dangers in the climate-change debate: smug groupthink. These researchers, some of the most prominent climate experts in Britain and America, seem so focused on winning the public-relations war that they exaggerate their certitude — and ultimately undermine their own cause.

…Contempt for critics is evident over and over again in the hacked e-mail messages, as if the scientists were a priesthood protecting the temple from barbarians. Yes, some of the skeptics have political agendas, but so do some of the scientists. Sure, the skeptics can be cranks and pests, but they have identified genuine problems in the historical reconstructions of climate, as in the debate they inspired about the “hockey stick” graph of temperatures over the past millennium.

It is not unreasonable to give outsiders a look at the historical readings and the adjustments made by experts like Harry. How exactly were the readings converted into what the English scientists describe as “quality controlled and homogenised” data?

Trying to prevent skeptics from seeing the raw data was always a questionable strategy, scientifically. Now it looks like dubious public relations, too.

Judith Curry

In my opinion, there are two broader issues raised by these emails that are impeding the public credibility of climate research: lack of transparency in climate data, and “tribalism” in some segments of the climate research community that is impeding peer review and the assessment process.

And further comment by Curry here

What has been noticeably absent so far in the ClimateGate discussion is a public reaffirmation by climate researchers of our basic research values: the rigors of the scientific method (including reproducibility), research integrity and ethics, open minds, and critical thinking. Under no circumstances should we ever sacrifice any of these values; the CRU emails, however, appear to violate them.

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Categories: climate change

>Adjusting multi-site and single site temperature data

2009 December 8 2 comments

> NIWA offer as their explanation for the temperature adjustments the paper

  • Rhoades, D.A. and Salinger, M.J., 1993: Adjustment of temperature and rainfall measurements for site changes. International Journal of Climatology 13, 899–913.

Though they do not link to it nor give a digital object identifier (doi:10.1002/joc.3370130807).

The abstract states

Methods are presented for estimating the effect of known site changes on temperature and rainfall measurements. Parallel cumulative sums of seasonally adjusted series from neighbouring stations are a useful exploratory tool for recognizing site-change effects at a station that has a number of near neighbours. For temperature data, a site-change effect can be estimated by a difference between the target station and weighted mean of neighbouring stations, comparing equal periods before and after the site change. For rainfall the method is similar, except for a logarithmic transformation. Examples are given. In the case of isolated stations, the estimation is necessarily more subjective, but a variety of graphical and analytical techniques are useful aids for deciding how to adjust for a site change. (Emphasis added)

I did not fully follow all the maths in the paper. It was not particularly complex but I would need to spend some time doing examples to completely grasp it.

In the introduction they define “site change”,

We use the term site change to mean any sudden change of non-meteorological origin. Gradual changes can seldom be assigned with any certainty to non-meteorological causes. Where long-term homogeneous series are required, for example, for studies of climate change, it is best to choose stations that are unlikely to have been affected by gradual changes in shading or urbanization. This is no easy task. Karl et al. (1988) have concluded that urban effects on temperature are detectable even for small towns with a population under 10000.

…This paper is concerned with the estimation of site-change effects when the times of changes are known a priori, such as when the station was moved or the instrument replaced.

The paper predominantly discusses adjustments to data when there are site changes and there are surrounding overlapping data sets (nearby thermometers) that can be used to assess whether there needs to be adjustment.

Later in the paper when discussing sites that have no overlapping data the authors state,

Such an adjustment involves much greater uncertainty than the adjustment of a station with many neighbours. A greater degree of subjectivity is inevitable. In the absence of corroborating data there is no way of knowing whether an apparent shift that coincides with a site change is due to the site change or not. However, several statistical procedures can be used alongside information on station histories to assist in the estimation of the effect of a site change. These include graphical examination of the data, simple statistical tests for detecting shifts applied to intervals of different length before and after the site change, and identification of the most prominent change points in the series independently of known site changes. Finally, a subjective judgement must be made whether to adjust the data or not, taking into account the consistency of all the graphical and analytical evidence supporting the need for an adjustment and any other relevant information.

Moreover when they apply this adjustment to a station in Christchurch to demonstrate their method comparing with the more accurate method used earlier in the paper they significantly over estimate the difference,

The 1975 site change at Christchurch Airport is somewhat overestimated, when compared with the neighbouring stations analysis. The contrast between the estimates based on 2 years data before and after this site change is particularly marked. For the neighbouring stations analysis the estimate is 0.45°C (Table TI); for the isolated station analysis the estimate is 1.58°C (Table V). This is to be expected when a site change coincides with an actual shift in temperature, as occurred in this case. The isolated station analysis then estimates the sum of the site change effect and the actual shift.

In their conclusion they note,

Adjustments for site changes can probably never be done once and for all. For stations with several neighbours, the decision to adjust for a site change usually can be taken with some confidence. The same cannot be said for isolated stations. However, large shifts can be recognized and corrected, albeit with some uncertainty. Ideally, for isolated stations, tests for site change effects would be incorporated into the estimation of long-term trends and periodicities as suggested by Ansley and Kohn (1989). This is not practicable at present on a routine basis, but may be in the future.

And

Whatever adjustment procedures are used, the presence of site changes causes an accumulating uncertainty when comparing observation that are more distant in time. The cumulative uncertainties associated with site change effects, whether adjustments are made or not, are often large compared with effects appearing in studies of long-term climate change. For this reason it is a good idea to publish the standard errors of site change effects along with homogenized records, whether adjustments are made or not. This would help ensure that, in subsequent analyses, not too much reliance is placed on the record of any one station. (Emphasis added)

Ironically, the methods suggested in this paper do not include the method used by NIWA in defending their Wellington data.

>What it means to explain adjustments

2009 December 7 Leave a comment

>After the New Zealand Climate Science Coalition released it’s paper, “Are we feeling warmer yet?” there was much discussion around the necessity of adjusting data. Focus was on the Wellington data though, as I pointed out, there is no overlap between Thorndon and other sites given. So adjusting to a nearby site of the same elevation, while possibly reasonable, can be questioned: busy international airport, large amounts of asphalt (especially when considering the multi-decadal time difference), urbanisation effects. Even disregarding that Anthony Watts gives Kelburn a rating of CRN=4.

This is an issue of the legitimacy of specific adjustments. The paper above acknowledges the figures are adjusted, they question why,

At a minimum, the adjustments made to the official NZ temperature record must be made public.

Treadgold had also said,

The real issue is that adjustments were made by NIWA and not acknowledged publicly on their website….

NIWA responded initially to the paper with this article and referencing the same Wellington data. They also stated concerning the temperature adjustments (corrections) (as I mentioned in my earlier post),

NIWA climate scientists have previously explained to members of the Coalition why such corrections must be made.

NIWA have also expanded their explanation displaying the Wellington graphs previously shown by Gareth Renowden (as per my earlier post).

NIWA have also released their own graph from raw data. They used sites that have not been shifted since 1930.

I am not certain why they used a trend line without also including a smoothed line like they had for their earlier graph.

NIWA give more justification that New Zealand temperature is rising here. They mention several confirmatory records that show the temperature rise over the decades. And they refute several claims by the NZ Climate Science Coalition, specifically NIWA claims that the Coalition have had access to:

  1. the raw data
  2. the adjusted data (anomalies)
  3. information needed to identify the adjustments made by Dr Salinger
  4. information needed to develop their own adjustments.

The Coalition confirm that the raw data is available and they stated that in the original paper. The other 3 claims are not so clear. An email sent to the Coalition said that the adjusted (corrected) data was held by Salinger,

Dr Jim Salinger maintains the “corrected” dataset and is the best person to talk to you about it.

But the Coalition deny receiving all the corrected data despite requests for it. Further, the 7 sites labelled on the data they received differed from the 7 sites that were specified in other correspondence from NIWA. And even if they had the information to identify the adjustments (item 3 above), they do not have the reasoning as to why this was done. This also makes it difficult to do item 4. When the Coalition analyses the Hokitika data they see no good reason as to why it is adjusted as it has been. Wellington is the example that is repeatedly mentioned. What of Hokitika and the other 5 stations?

Which raises the issue of the post title. What the Coalition want, and what NIWA should have had available on their site before any requests were made, is both the raw data and the adjusted data, and the explanation of the adjustment. NIWA offer as their explanation this paper (doi:10.1002/joc.3370130807).

I will return to this paper tomorrow but the response from NIWA misses the point. It is not a methodology or technique of temperature adjustment the Coalition is asking for. It is why the adjustments were made for every adjustment.

  • Adjustment A was made in this data set because of a site change. And the reason for this amount of change is because we took sites 1, 2 and 3 into account.
  • Adjustment B was made because of a change in thermometer.
  • Adjustment C was made to take into account the urban heat island effect.

One can mention the methodology as well if helpful,

  • Adjustment… following the method of Smith for isolated stations.

It is then one can reproduce the adjusted data and discuss the merits of each adjustment.

  • What about sites 4 and 5, they would attenuate the data by 0.1 °C.
  • You haven’t allowed for wind effects which are relevant before 1965 because…
  • Smith was developed for continents and has not been validated for temperate islands, the method of Jones is more appropriate.

The when and why is needed so that this discussion can be had.

Categories: clarity, climate change

>NIWA defends it adjustment of data

2009 November 27 Leave a comment

>NIWA have released a statement that the data that shows a warming trend in New Zealand over 100 years was adjusted.

NIWA’s analysis of measured temperatures uses internationally accepted techniques, including making adjustments for changes such as movement of measurement sites.

Though the paper (and my post yesterday) suggest adjustment was the likely explanation. However the graph and the surrounding paragraph fail to mention the data is adjusted. I read significant numbers of scientific papers and they are always referencing the raw and the adjusted data labelling both. There are statistical issues with some of these papers but this is not one of them.

NIWA go on to say,

Such site differences are significant and must be accounted for when analysing long-term changes in temperature. The Climate Science Coalition has not done this.

NIWA climate scientists have previously explained to members of the Coalition why such corrections must be made. NIWA’s Chief Climate Scientist, Dr David Wratt, says he’s very disappointed that the Coalition continue to ignore such advice and therefore to present misleading analyses.

Unfortunately this comment fails to identify and thus address the issue which is: “why” is not the question the Coaliltion is asking; it is “what” and “how”. What is the adjustment? and how have you done it? Treadgold (an author of the paper) writes,

We cannot account for adjustments, because we don’t know what they are. We ask only to know the adjustments that have been made, in detail, for all seven stations, and why.

Transparency demands that the specific reasons for data adjustment be given.

  • What stations have been adjusted?
  • When were they adjusted?
  • Is the adjustment stepwise or a trend?
  • Is there overlap of data when stations are shifted?
  • Does the overlapped data show good correlation?
  • Have adjustments been modified in subsequent years? Why?
  • What is the computer code that applies the adjustment?

This sort of information allows others to review the legitimacy of such decisions. And various groups can argue for and against these reasons and the weighing various reasons should be given.

Why the secrecy? The refusal to be open with data and theories is looked upon with suspicion, and rightly so.

Gareth Renowden writes a post explaining why adjustments are made to the data. The excessive rhetoric notwithstanding, the argument is plausible. But it still leaves questions unanswered. While the Wellington station may just be used an example, what of the other 6 stations? Wellington may show a rise after adjustment, but this will be diluted when averaged across all the station unless they all showed a rise. It they did what is the explanation for them.

Though I am not fully convinced with NIWA’s explanation. The Airport and Kelburn temperatures seem well correlated, with Kelburn cooler being at a higher altitude. And Thorndon and Airport are both at the same elevation (sea level). But there is no correlation established between Thorndon and the other 2 locations.



Elevation is not the sole determiner of temperature. There may be other considerations that make Thorndon and the Airport different temperatures. If so, then the adjustment down of the Thorndon data may be excessive. It should be easy to set up further measurements at Thorndon currently and see how they correlate to Kelburn and the Airport. If they all correlate well then we can establish a more accurate correction factor for the pre-1930 Thorndon data.

>New Zealand not warming?

2009 November 26 18 comments

>It seems to residents that the country has not being getting warmer over the last decade. Such that advocates of global warming prefer the term climate change so that any weather anomaly can be attributed to anthropomorphic global warming. And people are willing to parrot claims that some parts of the world will get colder (this may be a prediction of the theory but should encourage one to cautiously consider these claims).

The New Zealand National Institute of Atmosphere and Water Research (NIWA) do not show significant change since 2000 but they do show an increase over the last century as seen in this graph.

Graph. Mean annual temperature over New Zealand, from 1853 to 2008 inclusive, based on between 2 (from 1853) and 7 (from 1908) long-term station records. The blue and red bars show annual differences from the 1971 – 2000 average, the solid black line is a smoothed time series, and the dotted line is the linear trend over 1909 to 2008 (0.92°C/100 years).

Yesterday the New Zealand Climate Science Coalition released an article challenging this rise using NIWA’s own data. They plotted the temperatures from the NIWA source data and got this graph.

Whereas the first shows a rise of ~1°C per century, the second shows no discernable rise. The difference between the 2 graphs? The second uses raw data, the first (probably) has adjusted the data.

About half the adjustments actually created a warming trend where none existed; the other half greatly exaggerated existing warming.

There are legitimate reasons why data can and should be adjusted. Cities grow and hence warm so later temperatures may be warmer, especially overnight. Different thermometers may be used that show a consistent measurable difference. But there are 2 comments to make about adjusting data. Firstly adjusted data should be labelled as such with the unadjusted data displayed alongside it and the factors the data was adjusted for.

Secondly, it makes a difference whether adjusting data removes or produces an association. Frequently differences in data are seen because they attributes of the data sets are different. If we compare test scores between highschools to create a league table it may be reasonable to correct for number of children in different grades as some schools may have more students at higher levels, or one school may only let its brightest children sit the test. But we should be more cautious about accepting an association that only appears after adjustment. It is not that there can be no difference, rather it is that enough statistical manipulation can show a difference and the reasons for the adjusted variables are then argued after the fact.

If you do find a difference after adjustment you need to check your adjustment factors are not associated with the variable that is under consideration, in this case you cannot adjust for time as time changes are what is being looked for; and you must validate your adjustment with an independent data set.

On top of the release of emails and computer code from the now infamous Climate Research Unit at the University of East Anglia, UK; perhaps there might be some room for debate around the issues of climate change. Is it happening? Are humans responsible? Would it be detrimental? Should we pay attention to scientists who refuse to reveal their data and formulae?

>First day of winter

2009 May 31 2 comments

> Winter last year here was probably average, the year before that was very cold. The recent summer was reasonably warm with moderate heat waves over the country in late December early January. Late Autumn seems wetter and colder than usual.

All this is my subjective assessment based on memory. I have not checked the averages over the last few years and made comparisons. It is likely to be a reasonable assessment though, and I am happy to be corrected by locals who disagree.

I am going to make a prediction for this year’s winter. It may seem somewhat suspicious being so close to winter, especially given the recent cold snap, but I have been thinking about this since summer.

So I predict a colder than usual winter for this year.

My reasons for this are unrelated to anthropomorphic global warming because I remain a global warming sceptic. My reasons are

  • Sunspot minimum
  • La Nina
  • Pacific Decadal Oscillation

Not only are we in a sunspot minimum, we are in a particular long one; reminiscent of the quiet periods in late 19th century, though not to the extent of the Maunder minimum.

If the southern Pacific ocean temperature anomaly is greater than 0.5 °C for 5 periods it is an El Nino, if it is less than –0.5 °C it is a La Nina. Temperatures that show less excursion are neither. El Ninos and La Ninas are of variable duration but about 1–2 years. The last cycle was a La Nina ending mid 2008. The current anomalies are less than –0.5 °C for the last 4 cycles, so if the anomaly for March-April-May is also less than (or equal to) –0.5 °C then we are in another La Nina.

The Pacific Decadal Oscillation has a cycle of about 20–30 years. It has been in a warm phase since 1977. It (probably) switched to a cool phase in 2008.

All 3 features are associated with temperature. The ocean patterns may be reflective of temperature rather than a cause of it, but even if we don’t know the cause we can recognise the correlation. The current conditions of each of them individually suggest cool temperatures. All 3 of them in cool mode suggests to me that this winter is going to be colder than average.

>Are proofs of global warming actually myths?

2009 May 3 4 comments

> Andrew Bolt offers a refutation of several evidences of global warming* which he labels “myths.” The 10 proofs of global warming he refutes are

  1. The world is warming
  2. The polar caps are melting
  3. We’ve never had such a bad drought
  4. Our cities have never been hotter
  5. The seas are getting hotter
  6. The seas are rising
  7. Cyclones are getting worse
  8. The great barrier reef is dying
  9. Our snow seasons are shorter
  10. Tsunamis and other disasters are getting worse

The second is interesting, the amount of ice in the Antarctic has increased over the last 3 decades. That issue 1 is a myth is a pity as I think the biosphere would be more productive if it were warmer, especially in temperate and polar climes. Hopefully the higher CO2 will increase biomass despite lack of temperature increase.

He tackles issue 4 via record high temperatures. While interesting, it is not the best way to address it. Cities probably are warming via the urban heat island effect. (Though he is refuting claims, not suggesting these are the best claims).


*I would have linked to the Herald article but it has been taken down (as per some news sites’ bizarre policies of removing material older than some arbitrary duration). I have not reviewed the site linked to above that has a copy of the story. And here is an attempted refutation of Bolt.

Categories: climate change