Tuesday, December 07, 2004


Louis Hissink comments:

Finally a short note about Temperature - that property of physical matter that seems to get so much attention these days. Roy Spencer, above, noted that the climate models might be in error. Well there is a fairly obvious error made in estimating the global surface temperature.

It comes about when intensive variables are used as the basis of quantitative analysis and explained in intensive and extensive variables.

Examples of extensive variables are mass, length, area and doing basic arithmetic on them, like addition, is possible. So adding 5 grams of water to 10 grams of water gets you 15 grams of water. No argument about this I suspect.

Examples of intensive variables are ore-grades in grams per tonne, specific gravity or density and temperature. So if I have 5 grams of water at 20 degrees Celsius and 10 grams of water at 30 degrees Celsius does not mean I have 15 grams of water at 50 degrees Celsius. The problem here is that intensive variables are not quantities - you can't go to your local supermarket and buy 20 degrees Celsius of frozen prawns, for example.

And herein lies the fundamental problem of computing the earth's "global temperature" - you cannot simply add up all the mean temperatures, then divide by the total number of measurements to get the overall mean temperature - because intensive variables are not additive. And weighting those temperatures by "urban" effects does not improve the computation.

However the physical quantity which is additive is the amount of thermal energy for a body of atmosphere which is computed as the mass of atmosphere multiplied by its temperature and its specific heat based on the relative humidity of the air when the temperature was recorded. It is a simple concept and usually described in Physics 101 texts as the method of mixtures.

A more accurate estimate is made when the weather stations are assigned to the type of land they are on - and one would need to draw boundaries along urban areas and so forth. These concepts are thoroughly described in any good geotatistical text and not detailed here. Thus each temperature station is assigned an area of influence based on the type of physical environment it is linked to. It is then a simple matter to assign the third dimension to give us volume of atmosphere for that specific area, for which we can measure its density, humidity and temperature. This then allows us to compute the quantity of thermal energy associated with that part of the atmosphere that is linked to a particular weather station. This is repeated for all the rest of the weather stations, divided by the total mass times specific heats to obtain the final global temperature.

This is how the mean global temperature should be estimated. Oh and there is no such thing as an average global temperature either, since one object cannot have an average anything.

Of course simply adding up the temperatures and dividing by the total number of measurements does have a valid physical meaning - it is simply the average temperature of the physical thermometers themselves, assuming physically identical thermometers. The problem is that when a temperature is recorded, it is the thermal state of the thermometer and the mass of substance it is in thermal equilibrium with. The temperature is associated with two physical objects, and estimating the average temperature of the thermometers is one calculation while the temperature of the atmosphere another.

And of course we must not forget the mass of the earth at its temperature, because it too is part of the thermal system that the atmosphere is part of, and so must be factored into the estimate of the global mean surface temperature.

Therefore it is quite possible that the discrepancy between the global surface temperatures and the MSU temperatures of the lower troposphere is the result of faulty computation of the surface temperatures rather than anything else.


The claims get wilder as the contrary evidence piles up

Reuters recently reported that "A study of a 2003 heatwave in Europe may give Pacific islanders and environmentalists new ammunition for legal cases blaming the United States for global warming, advocates said on Thursday."

"Legal cases"! What fun. Just mentioning legal cases is supposed to create the impression of firm evidence, of course. The Article in Nature (PDF) is entitled "Human contribution to the European heatwave of 2003" by Peter A. Stott, D.A. Stone and M.R. Allen. The introduction reads:

The summer of 2003 was probably the hottest in Europe since at latest AD 1500, and unusually large numbers of heat-related deaths were reported in France, Germany and Italy. It is an illposed question whether the 2003 heatwave was caused, in a simple deterministic sense, by a modification of the external influences on climate- for example, increasing concentrations of greenhouse gases in the atmosphere- because almost any such weather event might have occurred by chance in an unmodified climate.However, it is possible to estimate by how much human activities may have increased the risk of the occurrence of such a heatwave. Here we use this conceptual framework to estimate the contribution of human-induced increases in atmospheric concentrations of greenhouse gases and other pollutants to the risk of the occurrence of unusually high mean summer temperatures throughout a large region of continental Europe. Using a threshold for mean summer temperature that was exceeded in 2003, but in no other year since the start of the instrumental record in 1851, we estimate it is very likely (confidence level >90%)9 that human influence has at least doubled the risk of a heatwave exceeding this threshold magnitude.

So what does this new evidence amount to? It is no new evidence at all, in fact, It is just a "conceptual framework"! And it is in any case ludicrous to say that they can establish 90% confidence that human influence has anything to do with this. In the Reuters article they quote various environmentalists calling this "evidence" and an "important step". It is in fact just an exercise in number manipulation.


Many people would like to be kind to others so Leftists exploit that with their nonsense about equality. Most people want a clean, green environment so Greenies exploit that by inventing all sorts of far-fetched threats to the environment. But for both, the real motive is to promote themselves as wiser and better than everyone else, truth regardless.

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