Mar 31 2010

Smoking Gun: CRU Data Too Inaccurate To Detect AGW

Ross McKitrick has a long narrative up on how he has attempted to correct the sloppy math and unproven assumptions made by the IPCC and CRU (H/T Bishop Hill).  As you read this you should also be aware that inside the CRU data dump from last fall was a smoking gun document which clearly indicates CRU knows its data is incapable of detecting AGW levels to a tenth of a degree. To do so requires temperature data to be at least that accurate or better. You can’t measure to the inch with an unmarked yard stick.

I mentioned the document months ago in this post (and others) as evidence that the CRU temperature data DOES NOT have the accuracy required to support the IPCC claim to detect tenth of a degree changes over decades over the entire planet. The document is very interesting in that it shows for one year in the past (1969) the uncertainty in the CRU temp data grids (click to enlarge).

The data clearly shows that for 1969 the CRU temperature data sampling errors ranged from 1°C for most of the world and up to 4.5°C for a lot of North America and Russia.

As the McKitrick article notes the entire AGW house of cards relies on how one question is answered:

“It would be fine if the climate signal were large and the inhomogeneities were small. But it is the other way around. We are looking for changes measured in tenths or hundredths of a degree per decade, using data from weather stations where the inhomogeneities can easily shift the record by several degrees.”

There is no way a tenth of a degree signal an be detected when the data used has stated error levels of 1-4°C! I still don’t understand why this document has not been used to bludgeon the IPCC into admitting it’s conclusions are based on unsupported math.

But there is more damning admissions in the document (written in 2005)

We have not yet made final estimates of all the uncertainty components, but we expect the sampling error to dominate the uncertainties of monthly gridded fields. Figure 4 shows the estimated sampling errors for the gridded fields of figure 3″

Figure 4 is the graph above with the huge sampling errors. The bold text says it all. CRU has not proven even to themselves they have the accuracy stated in IPCC literature, based on CRU data. Here are a list of CRU ASSUMPTIONS at the time of writing this document, assumptions which have never been proven as far as I know:

There are three different sorts of uncertainty to be considered:

• Uncertainties in the station data:

– Measurement error: following [5] we estimate this as 0.04C on monthly average temperatures.
– Uncertainty in homogenisation corrections: we are estimating this by examining records of corrections performed at CRU, and by examining differences between corrected and uncorrected data provided by the Austrian and Canadian national met. services.
– Uncertainty in the climatologies: this is only important where station data is incomplete over the climatology period; we are estimating it by exploring the effect of removing data from stations with complete coverage.

• Uncertainties in the gridded fields:

– Effects of the station uncertainties: the combined effect of the uncertainties described above.
– Sampling error: we are adapting the methods of [6] to work on a flexible grid.

• Uncertainties in the bias corrections. Following [5], we are considering two bias corrections: instrument exposure changes and urbanisation. we are adapting the methods of [5] to work on a flexible grid.

Call me crazy, but it looks to me that CRU knew it had not assessed and quantified the error in their data products, and never made that little detail public to all the people who were led to believe the data was accurate enough to detect AGW levels claimed.

Update: Then there are errors created by making up temperatures out of thin air:

The oddity about the picture is that we are given temperature data where none exists. We have very little temperature data for the Arctic Ocean, for example. Yet the GISS map shows radical heating in the Arctic Ocean. How do they do that?

The procedure is one that is laid out in a 1987 paper by Hansen and Lebedeff In that paper, they note that annual temperature changes are well correlated over a large distance, out to 1200 kilometres (~750 miles).

Does anyone really think a temperature reading in Los Angeles, CA can be used to precisely estimate the temperature in Eugene, OR? I mean anyone old enough to read?

11 responses so far

11 Responses to “Smoking Gun: CRU Data Too Inaccurate To Detect AGW”

  1. […] This post was mentioned on Twitter by Suhr Mesa. Suhr Mesa said: CRU Data Too Inaccurate To Detect #AGW Again, can't make this up. #p2 #tcot #globalwarming #algore #poetry #sgp #left […]

  2. Frogg1 says:

    AJ, does this pass the smell test? It seems like there is conflicting things in the article to me.

    Inquiry: Climate data not manipulated
    British lawmakers say science sound, but want transparency

  3. AJStrata says:


    It is what you get when politicians put on a show to cover their butts. You can read a good response at Bishop Hill (blog roll on right). The report is full of statements which, if they were true, science would be dead.

  4. archtop says:

    “The procedure is one that is laid out in a 1987 paper by Hansen and Lebedeff In that paper, they note that annual temperature changes are well correlated over a large distance, out to 1200 kilometres (~750 miles).”

    The original Hansen and Lebedeff paper is here .

    The money quote…

    “At middle and high latitudes the correlations approach unity as the station separation becomes small; the correlations fall below 0.5 at a station separation of about 1200 km, on the average. At low latitudes the mean correlation is only 0.5 at small station separation.”

    If you look at Figure 3, the correlation is really pretty poor overall, but it’s hard to tell because of the way the graph was drawn.

    I any case it is certainly NOT TRUE that “annual temperature changes are well correlated over a large distance…”.

    The paper also contains this curious statement:

    “We show that meaningful global temperature change can be obtained from only the meteorological station data; thus we avoid the ambiguity inherent in combining sea surface temperatures with surface air station data as well as the difficulties encountered with any marine (surface air or sea surface) temperatures due to temporal changes in the nature of ships.”

    So using both land and sea data are like comparing apples to oranges?

    Finally, check out their convoluted algorithm for computing “temperature change” in arbitrarily defined “boxes”, described in section 3. No wonder GISTEMP is the worthless junk that it is…

  5. AJStrata says:


    Thanks for the insights. These clowns have been playing scientist in their little backwater niche, and when the Klieg lights hit them they were shown to be in way over their skill sets.

    There are no tested and validated products showing temperature indexes to the levels claimed anywhere. Everyone just assumed these PhDs knew what they were doing – and they didn’t.

  6. Kate4 says:


    ……….it seemed as if we had the warmists on the run.

    ……..a more realistic appraisal might suggest that we have not even dented the underlying agenda.

    Miliband is paving the way to get the Kyoto treaty protocols back on track for agreement in Mexico later this year, as part of an international treaty. And he wants to pull in developing countries into the treaty maw, with them offering some “commitments” of their own – more cosmetic than real – in order to cement in the developed (or “Annex 1”) countries into the deal.

    This move comes alongside a meeting between Gordon Brown and “billionaire financier” George Soros, Obama’s economic adviser Larry Summers, economist Lord Nicholas Stern and other finance ministers. In parallel, they were working on stitching up the financial package which is so central to the real agenda.

    Their headline goal is to raise $30bn (£20bn) a year immediately and $100bn a year by 2020, ostensibly “to enable developing countries to adapt to climate change.”

    Whatever mechanisms are eventually agreed, however, of one thing there can be absolute certainty. Very little of the money allocated to this cause will ever reach its stated destination. As with the current aid programme, most of it will be soaked up by banks, finance houses, investors and brokers, in fees and commissions. Huge amounts will line the pockets of governments in the recipient countries, and NGOs will grow fat and rich.

    Britain brandishes olive branch to restart global climate change talks

  7. […] GISS has so many problems with its approach they are in for a rough ride too, especially if the GOP takes over Congress this fall. Expect a grilling on why GISS assumes a thermometer in Los Angeles, CA can be used to determine the temperature in Eugene, OR. […]

  8. […] The Strata-Sphere » Smoking Gun: CRU Data Too Inaccurate To Detect AGW. April 17th, 2010 | Category: Uncategorized | Comments are closed | […]

  9. […] via The Strata-Sphere » Smoking Gun: CRU Data Too Inaccurate To Detect AGW. […]

  10. […] trickery, a simple sleight of hand which uses one measurement to cover 1200 km (~750 miles). As I noted before, this is like using a temperature reading in Los Angeles, CA to reflect temperatures in Bend, OR. […]