NCPA - National Center for Policy Analysis


March 21, 2007

Discussions on global warming often refer to "global temperature."  Yet the concept is thermodynamically -- as well as mathematically -- an impossibility, says Bjarne Andresen, a professor at the Niels Bohr Institute at the University of Copenhagen.

Andresen explains that while it is possible to treat temperature statistically locally, it is meaningless to talk about a global temperature for the entire planet.  For instance:

  • If temperature decreases at one point and it increases at another, the average will remain the same as before, but it will give rise to an entirely different thermodynamics and thus a different climate.
  • If, for example, it is 10 degrees at one point and 40 degrees at another, the average is 25 degrees; but if instead it is 25 degrees in both places, the average is still 25 degrees.
  • These two cases would give rise to two entirely different types of climate, because in the former case one would have pressure differences and strong winds, while in the latter there would be no wind.

A further problem with the extensive use of the global temperature is that there are many ways of calculating average temperatures, according to Andresen.  For example:

  • Take two equally large glasses of water -- one glass with a temperature of 0 degrees and in the other it is 100 degrees -- adding these two numbers and dividing by two yields an average temperature of 50 degrees; that is called the arithmetic average.
  • Take the same two glasses of water at 0 degrees and 100 degrees, and multiply those two numbers and take the square root and you will arrive at an average temperature of 46 degrees; this is called the geometric average (the calculation is done in degrees Kelvin which are then converted back to degrees Celsius).
  • The difference may be only 4 degrees, but it is that energy which drives all the thermodynamic processes which create storms, thunder, sea currents, etc.

Source: Editorial, "Researchers Question Validity Of A 'Global Temperature,' ScienceDaily, March 18, 2007 and "The Future of Coal; Options For a Carbon Constrained World," Massachusetts Institute of Technology, March 14, 2007.

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