Who is Steve McIntyre?
Stephen McIntyre has been a long-time mining industry executive, mostly working on the “stock market side” of mining exploration deals. He published a blog called Climate Audit where he attempts to analyse in sometimes long and extensive detail the work of climate change scientists where he documents “statistical mistakes” in peer-reviewed scientific literature. …
McIntyre has been described as a “persistent amateur who had no credentials in applied science before stepping into the global warming debate in 2003” and has been a prominent critic of temperature records that suggest increasing global temperatures over the past 1000 years.
As of 2003, McIntyre had worked in the mineral business for 30 years and he has been an officer or director of small public mineral exploration companies for over 16 years…
In February, 2014, he put up four blog posts attacking Dr. Michael Mann in relation to Mann’s defamation suit against Mark Steyn et al, claiming in those posts that Mann had “misrepresented the findings of reports and inquiries into his work and the work of other climate scientists in relation to the so-called “climategate” affair, when the emails of scientists at the Climatic Research Unit at the University of East Anglia were illegally hacked and then published.” (desmogblog.com)
Today, McIntyre’s blog posted a lengthy “fisking” (sort of) written by Jean S, of the climategate emails. The focus is on the famous “Hockey Stick” curve produced by Mann and others just prior to 2000. This graph is an assembly of carefully vetted climate records including proxies and the modern instrumental record. The different sources of information used to show dramatic 20th century warming are well documented in Mann’s publications and further documented in freely distributed supplementary information. Two objections seem to have been raised by climate science denialists such as McIntyre and others. One is that one of the proxies, certain tree ring data, show cooling or at least a lack of warming. The other is that the graphic representation of 20th century warming uncritically combined proxy data and instrumental data.
Denier Complaints About Climate Proxies Are Based On Ignorance Of The Science
A proxy, or proxyindicator, is a natural system that leaves a recoverable residue that varies in some measurable or observable way, such that the variation may correspond to a natural variation happening in the world at the time the proxy was being formed. For example, the ratio of Oxygen-16 and Oxygen-18, two stable isotopes of that element, in Oxygen incorporated in stable form (in biogenic tissues, for example) indicates the ratio of these isotopes in the ambient environment, which in turn, indicates the amount of each element available at the time, which in turn, indicates how much of each type of oxygen is trapped in glacial ice (which tends to have more Oxygen-16 because glaciers are ultimately made of vapor, which is isotopically light). Oxygen isotope ratios of materials recovered from deep sea cores indicate the march of glacial formation and melting over long periods of time.
The first of these two objections to Mann’s work, and other work, relies on naiveté among potential readers about proxyindicators. As is the case with all scientific data, all proxies are suspect, and all proxies have the potential of varying in sensitivity over time. Scientists must always evaluate the quality of the data they use, and not accept it uncritically.
For example, say you wanted to estimate the flow of a major river over time. You could measure how much silt is deposited on the river’s flood plain by taking Carbon-14 samples at numerous depths in the floodplain. A greater depth between samples separated by similar amounts of time might mean more flooding. But, as the flood plain matures and raises in elevation, the frequency of floods year to year may decrease, causing a decline in the rate of siltation, and thus, apparent water flow in relation to the actual water flow. Furthermore, at some point, the flood plain is essentially filled up, and flooding overbank happens elsewhere along the river, and no longer (or infrequently) at your sample site. This is a decline in the usefulness of the proxy to the point that you have to simply stop using it.
Another example. Say you want to use pollen counts form layers found in mud at the bottom of a lake, the layers having been recovered from cores sunk in the lake. Assume your lake is in a region that started out as grassland but slowly became more forested. Trees act as pollen filters. Pollen wafting across the landscape is caught in the trees. In the early part of the lake core data, pollen may be introduced from many kilometers away from wind blown plants (grasses, some trees) and from similar distances from plants that do not distribute pollen via wind, but in small quantities (such plants produce way less pollen than wind pollenated plants) via streams that enter the lake. Over time, however, trees will grow up first around the lake, then over a larger area of the landscape. Windblown pollen from grasses is less likely to get into the pond, and there may be less of that pollen because trees are replacing grassland. Meanwhile, the longer distance stream carried pollen may continue to represent the original catchment of pollen. But, if there are changes in rainfall patterns, that could change too. People looking at pollen in lake cores may use an independent measure, such as the amount of iron in the sediment, to indicate how much water comes in from longer distances via streams vs. how much comes in from groundwater and as direct rain. They will use studies of pollen taphonomy, which look at changes in “pollen rain” as forests develop, to calibrate the effects of trees on the wind blown grass pollen representation. At some point, near the top of the core, the tree pollen may be suddenly and dramatically reduced and the wind blown grass pollen may switch to mostly corn or wheat. This is farmers coming in and completely changing the environment. The core from that point on up may become useless. In sum, the entire core has to be analyzed as a dynamic, changing proxy where some of the changes are important information about the changing environment, while other changes are indicative of an increase or a decline in sensitivity of the proxy as an indicator of what is being studied.
Something similar is going on with the tree ring data Mann used. At around 1960 the ability of the tree ring data to represent regional temperature declines and the tree rings become useless. Prior to that time the data should be used. After that time the data should be discarded.
A proxy is not a pre-calibrated consistent source of information. It is a method that uses measurements of recovered material that allow the reconstruction of an ancient process. But that requires understanding the process well enough to develop a way of determining when the proxy is being helpful and when it is providing noise. A good amount of the research on ancient paleoclimate and paleoecology is about how the proxies work. With this research it is possible in many cases to evaluate the utility of a proxy at a given location, and furthermore, to assess which parts of the proxy can be used, which parts need to be further calibrated, and which parts need to be ignored because of a decline in their usefulness.
We see climate science deniers claiming, for example, that the tree ring proxy used by Mann needs to be used “all or nothing.” This is nothing more than ignorance of how paleoclimatology works.
Complaints About The Hockey Stick Graph Are Not Valid
McIntyre’s arguments (along with others) about the graph are middle-school level obfuscation of the point. The scientists who published the original Hockey Stick graph went through pains to be clear about what information was going into which part of the overall curve. Subsequent renditions of the same data, or similar sets of data with new information added, range across the board from highly complex constructs showing the different sources of the data, error ranges, etc. to those that simplify by drawing a simple curve of combined information. I wrote about this here, showing how this practice, of sometimes making a very complex thing simpler in a way that makes the point accurately, is done all the time.
The latest post on McIntyre’s site, completely misrepresented what happened with the Hockey Stick curve. Nowhere in the quoted emails is there any suggestion or approval or any indication by Michael Mann of seamlessly merging proxyindicator data and instrumental data. The original documents clearly show that this is not what happened at any stage.
Why Do McIntyre And Others Fabricate These Objections?
If you read JeanS’s post closely, s/he seems to be simultaneously implying that Mann created a falsified representation of how the data come together, while at the same time admitting he did not. This is an increasingly common tactic among climate science denialists. They can no longer totally make up what they are saying because they are too easily called on it, yet want to provide other denialists with fodder, and confuse anyone involved in policy, or who just wants to learn, with more confusion and less clarity.
The only way to accept or even seriously consider the arguments that climate scientists developing the Hockey Stick curve or similar research were involved in inappropriate shenanigans is to anchor oneself deeply in a mire of intentional ignorance. There seems to be only one reason to do that (other than simply being very, very ignorant): a commitment to anti-science activism, with the likely intention of damaging the translation of good science into useful policy.
This is something a mining industry executive might do out of self interest and to represent the interests of that industry. Is that the case here? There is a trick to help determine if that is the case. Follow the money.
The graphic depicted above is from here. It is a 2007 version o the often replicated and used “Hockey Stick.”
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