Climate Change & Tropospheric Temperature Trends

Part II: A Critical Examination of Skeptic Claims
  • Neglect of the most recent, and improved, analyses of the MSU product they did use (other than passing remarks) – most likely because the later products (Christy et al., 2003; 2004) show higher MSU TLT trends than the one they chose (Christy et al., 2000) and that one covers a time frame closer to the truncated period they analyzed.
  • A selection of only those AOGCM run periods and parameters that produce large discrepancies between troposphere and surface trends - including a choice of ocean component model for GISS SI2000 that although it has many merits for satellite era trend studies like theirs, cannot be used for the very studies of future climate change (the very turf on which they claim to have demonstrated AOGCM failings) and which consistently shows worse agreement with observation than at least two other SI2000 ocean components that are well suited to studies of future climate change – even though results based on one of these components was presented in the very Figure they cited, side-by-side with the one they did use (Hansen et al., 2002).
  • Surely DEA are aware of the various climate events that influenced the 1979-present tropospheric record, so they must know that one of the ENSO events they included (1982-83) was almost as large as they one they truncated their record to avoid. They have pointed out in many other forums how regionally and temporally variable the upper-air history is, and they are aware of the geographic limitations of both the surface and radiosonde records in comparison to the MSU record. So they must know that these differences will impact trend comparisons. Though their choice of Ocean A for use in their GISS SI2000 coupled model runs is commendable in many ways, they must have been aware that it was not the only choice available. In particular, they must have been aware that this component would not even be used for the very AOGCM based studies of future global warming that they are claiming to have refuted, and the ones they ignored not only could be, they yield better agreement with observations with the same comparisons used in their paper – a fact that was clearly apparent in the right half of the very figure they referenced. It is one thing to make mistakes – we all do, and that’s why there is a peer-review process that we all benefit from. But the errors and omissions in these two papers are serious enough that it is difficult to see how they could have been accidental. In light of this, it would be fitting for Douglass, Singer, and Michaels to either present adequate explanations for them, or retract both papers with apologies.

    McKitrick & Michaels (2004)

    But wait! There are more surprises in store. Though DEA claim to have defeated global warming, even they are forced to admit from their own cherry-picked data, that the northern hemisphere surface and troposphere records show significant warming trends. So having dropped “bombshells“ one and two, they move on to their next holy grail – an attempt to explain (or perhaps explain away) the observed northern hemisphere warming trends as due to something other than climate change. Returning to their Tech Central Station victory celebration, we’re told that,

    “As bad as things have gone for the IPCC and its ideologues, it gets worse, much, much worse.

    After four years of one of the most rigorous peer reviews ever, Canadian Ross McKitrick and another of us (Michaels) published a paper searching for "economic" signals in the temperature record. McKitrick, an economist, was initially piqued by what several climatologists had noted as a curiosity in both the U.N. and satellite records: statistically speaking, the greater the GDP of a nation, the more it warms. The research showed that somewhere around one-half of the warming in the U.N. surface record was explained by economic factors, which can be changes in land use, quality of instrumentation, or upkeep of records.”

    (Douglass et al., 2004c)

    The reference is to “bombshell” 3 - a paper published in May of this year by Michaels and University of Guelph economist Ross McKitrick (2004 – hereafter, MM) in which it is argued that 1979-2000 northern hemisphere warming trends are driven by “economic and social factors” rather than climate change. While this paper does not address the MSU record, it is worth a digression here because,

    1. MM have stated their intention to expand the study it describes to include the MSU record in the near future (Michaels et al., 2004), and as we shall see, they note in it that their conclusions agree with UAH Version 5.0 TLT trends, indicating that they see it as yet another vindication of that upper-air product.
    2. It is even more revealing of the selective, and at times even haphazard methods of its authors.
    3. DEA consider it to be the great missing link in global warming surface trends that their alleged surface-troposphere disparity portends.

    So how do MM go about testing an alleged link between global warming and economic activity? They constructed a model of global climate and economic activity as a linear combination of various parameterized independent variables categorized as Climate related, Economically related, and Socially related, plus a coefficient to account for unexplained residuals in each model run iteration. The parameters used were as follows,

    Climate Parameters

    • Surface pressure in dry regions (which they consider to be a proxy for local surface temperature).
    • Coal use (which they use as a surrogate for sulfate emissions).
    • Cosine of latitude ( Cos(L) ).
    • Coastal proximity, expressed as a dummy variable.

    Economic Parameters

    • Population.
    • Real per capita income (factored by population as a measure of the intensity of regional economic activity).
    • Scale of economic development activity as characterized by land use changes. urban heat island effects, and regional collection and maintenance of temperature records in rural vs. developed areas.
    • Coal growth rate.
    • National GDP growth rate.

    Social Parameters

    • Local literacy rates.
    • Number of months of missing temperature data by region.

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