A further problem with the extensive use of 'the global temperature' is that there are many ways of calculating average temperatures.
Example 1: Take two equally large glasses of water. The water in one glass is 0 degrees, 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.
Example 2: Take the same two glasses of water at 0 degrees and 100 degrees, respectively. Now 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 of 4 degrees is the energy which drives all the thermodynamic processes which create storms, thunder, sea currents, etc.
Claims of disaster?
These are but two examples of ways to calculate averages. They are all equally correct, but one needs a solid physical reason to choose one above another. Depending on the averaging method used, the same set of measured data can simultaneously show an upward trend and a downward trend in average temperature. Thus claims of disaster may be a consequence of which averaging method has been used, the researchers point out.
What Bjarne Andresen and his coworkers emphasize is that physical arguments are needed to decide whether one averaging method or another is needed to calculate an average which is relevant to describe the state of Earth."
March 20, 2007
The following excerpt from Science Daily seems a rational view that questions the alarmist claims about global warming and the use of 'average global temperature' to warn that earth is in for big trouble. The researchers are from Denmark and Canada.