There is a concept in psychology called Magical Thinking which may be characterised by perception of causal relationships where science can find none. An example is the cargo cult in the Pacific nations after World War 2. The natives of the region had observed during that war that aircraft delivered many useful goods: food, tools, clothing etc. After the armed forces left the region, the aircraft stopped arriving and so did the associated goods they had previously delivered. The natives built symbolic aircraft out of local materials in order to obtain a resumption of the goods that they called cargo. Of course the cargo never arrived because it wasn’t the shape of the aircraft that was the cause of the arrival of cargo during WW2.
In current CAGW climatology there is a similar magical association between two distinctly different physical concepts: temperature and energy. The latter can be in many forms so the preferred physical concept of energy in many circumstances is enthalpy, the “measure of the total energy of a thermodynamic system. It includes the system’s internal energy and thermodynamic potential (a state function), as well as its volume and pressure (the energy required to “make room for it” by displacing its environment, which is an extensive quantity). The unit of measurement for enthalpy in the International System of Units (SI) is the joule [J].”
To illustrate, sea level air at 25°C and 10% relative humidity (RH) has enthalpy of 30.4 kJ/kg. Sea level air at 25°C and 90% RH has enthalpy of 71.8 kJ/kg, ~2.4 times the energy despite the same dry bulb temperature. So, when climatologists (regardless of any associated beliefs) talk of a “Global Average Surface Temperature Anomaly” (GASTA) they refer to the averaging of temperatures regardless of the enthalpy (energy content) of the air that is sampled. This would be fine if it were temperatures that arrived at the Earth from the Sun, but it’s not. What arrives from the Sun is energy: electromagnetic energy that is mainly in the form of visible light, but includes ultraviolet and infra red photons too.
Let’s first look at what temperature is and what averaging temperatures might mean. Put simply, temperature is a measure of the rate of vibration of molecules in thermal equilibrium. In thermal equilibrium means that the molecules are all vibrating at the same rate. If you have a metal rod where one end is in a fire and the other in a bowl of ice water, then heat energy is flowing from the hot end to the cold end. There is no thermal equilibrium and hence no defined temperature. Similarly, the Earth is not in thermal equilibrium and hence has no defined temperature. If there were such a definition you might expect to find such at The National Institute of Standards and Technology (NIST).
Much of what is known about decadal climate change – and much of what appears on the evening weather forecast as well – comes from satellite-based remote sensing of microwave radiation at different levels in the Earth’s atmosphere. Microwave measurements are generally reported as the apparent temperature of the object being monitored. Yet, at present, there is no accepted brightness-temperature (radiance) standard for microwaves that can be used for authoritative calibration of microwave sensors, for resolving discrepancies between readings from different satellites, or for comparing one program’s results with another’s.
Weather and climate uses for microwave remote sensing measurements require that the observed temperature be accurate within 1 kelvin or less. But existing measurements cannot be made with that accuracy or reliability. “Right now,” says David Walker, Project Leader for Microwave Remote Sensing in PML’s Electromagnetics Division, “new data coming from nominally identical instruments can differ by as much as a couple of kelvin.”
Well there’s a good reason to accept the calculations of GISS and CRU then. They tell us that they calculate GASTA to an accuracy of a tenth of a Kelvin (Celsius degree). But try as he might, The Git cannot find on NIST’s website, in Oke’s Boundary Layer Climates or anywhere else a Standard Definition of either Earth’s temperature or GASTA. There might be a very good reason for this — several good reasons in fact.
Consider what we are doing when we calculate the average length (arithmetic mean) of a bunch of sticks. Let’s say we have three sticks of lengths 2, 4 and 5 metres. We can lay them end to end, measure that length (11 metres), divide by three (the number of sticks) and discover the average length to be 3.6 metres.
Now let’s try the same with temperatures. Let’s say we have three beakers of water, one at 0°C another at 10°C and the third at 20°C. Mix the contents of the beakers together, wait for thermal equilibrium and measure the result. Do this several times. At no time is there ever a temperature of 30°C (the sum of the three temperatures) unlike the stick example where there is a well-defined 11 metres of stick. Worse, depending on the ratio of liquid water to ice in the 0°C sample, the resulting temperature might well be an entirely different value to 10°C which is the average of the three temperatures. Indeed, repeat the experiment a sufficient number of times to sufficient accuracy and you might well deduce that there are an infinite number of possible average temperatures.
So, what exactly is happening here in the second example compared to the first? Length and ever so many other physical values are extensive. Extensive values can be legitimately averaged. Temperature and ever so many other physical values are intensive and therefore attempting to average them is said to be physically undefined.
The Global Average Surface Temperature Anomaly calculation is just such a physically undefined operation as described above. First, the individual average temperature at a recording station is calculated. At some stations this is the sum of the hourly temperatures divided by 24 (the number of hours in a day). At others the minimum temperature is subtracted from the maximum and the result divided by two. This average is called the median and in the sticks example above is 3.5 metres and clearly not the same value as the arithmetic mean (3.6 m).
These average temperatures of the sampled air (and water in the case of HadCRUT) are then further averaged together to be compared with the average of temperatures over a particular length of time. The current average is then differenced from the period of time average to generate the Global Surface Temperature Anomaly as a proxy for enthalpy.
While this might make sense to climatologists, to The Git’s philosophical mind it more closely resembles numerology than any kind of description of a well-defined physical reality. Cargo cultism. Magical thinking.
And here endeth this lesson.