Tuesday, March 20, 2007

So what's between good science and the earth warming hypothesis?

Eclectecon just posted
[http://www.eclectecon.com/] the following:

Chris Essex, Ross McKitrick, and Bjarne Andresen recently published a paper [Jl. of Non-Equilibrium Thermodynamics, Vol 32, 1 - 27, 2007] in which they demonstrate that using different metrics leads to different conclusions about whether the earth is really warming. Here is the abstract:
Physical, mathematical, and observational grounds are employed to show that there is no physically meaningful global temperature for the Earth in the context of the issue of global warming. While it is always possible to construct statistics for any given set of local temperature data, an infinite range of such statistics is mathematically permissible if physical principles provide no explicit basis for choosing among them. Distinct and equally valid statistical rules can and do show opposite trends when applied to the results of computations from physical models and real data in the atmosphere. A given temperature field can be interpreted as both ‘‘warming’’ and ‘‘cooling’’ simultaneously, making the concept of warming in the context of the issue of global warming physically ill-posed.
Their conclusion is strong [emphasis added]:
There is no global temperature. The reasons lie in the properties of the equation of state governing local thermodynamic equilibrium, and the implications cannot be avoided by substituting statistics for physics.... Since temperature is an intensive variable, the total temperature is meaningless in terms of the system being measured, and hence any one simple average has no necessary meaning. Neither does temperature have a constant proportional relationship with energy or other extensive thermodynamic properties.Averages of the Earth’s temperature field are thus devoid of a physical context that would indicate how they are to be interpreted, or what meaning can be attached to changes in their levels, up or down. Statistics cannot stand in as a replacement for the missing physics because data alone are context-free.Assuming a context only leads to paradoxes such as simultaneous warmingand cooling in the same system based on arbitrary choice in some free parameter. Considering even a restrictive class of admissible coordinate transformations yields families of averaging rules that likewise generate opposite trends in the same data, and by implication indicating contradictory rankings of years in terms of warmth.The physics provides no guidance as to which interpretation of the data iswarranted. Since arbitrary indexes are being used to measure a physicallynon-existent quantity, it is not surprising that different formulae yield different results with no apparent way to select among them. The purpose of this paper was to explain the fundamental meaninglessness of so-called global temperature data. The problem can be (and has been) happily ignored in the name of the empirical study of climate. But nature is not obliged to respect our statistical conventions and conceptual shortcuts. Debates over the levels and trends in so-called global temperatures will continue interminably, as will disputes over the significance of these things for the human experience of climate, until some physical basis is established for the meaningful measurement of climate variables, if indeed that is even possible.It may happen that one particular average will one day prove to stand outwith some special physical significance. However, that is not so today. Theburden rests with those who calculate these statistics to prove their logic and value in terms of the governing dynamical equations, let alone the wider, less technical, contexts in which they are commonly encountered.