Climate Sensitivity
Most scientists would agree that carbon dioxide and other trace gases cause a warming of the global climate as a result of absorption of the infra red radiation from the earth by their spectral bands. 
Weather forecasting meteorologists measure the many properties of the climate, and provide a daily presentation of their influence on the global climate. But they have never found evidence that trace gas concentrations are sufficiently important in forecasting even to require regular measurement.
Scientists involved with the Intergovernmental Panel on Climate Change (IPCC) argue that carbon dioxide and other trace gases are not only important, but even the only cause of climate warming since 1750 and responsible for further warming as the concentrations rise.
They characterise the extent of this warming by the Climate Sensitivity. which is essentially the additional temperature change, modified by feedbacks, of a doubling of the atmospheric concentration of carbon dioxide. It may be defined thus:
ΔTCS = ΔTT x ΔFCS /ΔFT
where:
ΔTCS is the Climate Sensitivity
ΔTT is the temperature change since 1750
ΔFCS is the radiative forcing from doubling carbon dioxide
ΔFT is the radiative forcing since 1750.
The earth does not possess a temperature and there is no procedure whereby its average temperature could be measured.
As a substitute, the IPCC has promoted a global temperature anomaly based on weather station and sea surface measurements. This suffers from several violations of mathematical and physical principles, well exposed in the early paper by Hansen and Lebedeff (1997) who launched it.
They assumed that the unreliable mean of the maximum and minimum temperatures from a weather station applied over a circle of 1,200 km. The globe was divided into 5º x5º squares, the weather stations from each area averaged once more and subtracted from the average temperature for a reference period.
The measurements are not from representative samples and even this absence of representativity changes with time. The number of stations varies and the entire sequence lacks acceptable uniformity and estimates of accuracy and bias.
It is assumed that apart from solar change or effects of volcanoes, all other temperature change since 1750 was caused by changes in ‘greenhouse gas’ concentrations. This assumption derives from the Framework Convention on Climate Change which stated:
“Climate change” means a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods.
This definition assumes that the natural climate properties measured by meteorologist are merely variable so that over a long period, such as that from 1750 to 2000, they could be assumed not to change at all but just vary.
Appendix II The IPCC 2013 Report lists figures for their temperature anomaly for every decade from 1750 to 2000. These are used with the table of figures for radiative forcing to calculate climate sensitivity.
The claimed temperature rise from 1750 to 2000 of 0.773ºC is below the accuracy of the daily weather forecast (±2.0ºC and ±1.0ºC bias) and well below any plausible estimate of accuracy or bias from the derivation of the record. The figure is simply without statistical significance.
Geologists know that there are changes of climate from natural reasons in every geological period, short or long, whether or not human influences existed. There have been several where carbon dioxide concentrations were not related to assumed temperatures.
The FCCC assumption that all natural climate properties are merely variable may not be true. Perhaps some or all of the claimed temperature change since 1750 had natural causes.
The First IPCC Report (1990) suggested that recent temperature increases could have been a recovery from the Little Ice Age (1550 -1850). Some increase was due to urban development and some to the persistent attempts to manipulate the record, as summarized by D’Aleo and Watts (2010).
The Mean Global Annual Surface Temperature Anomaly is now incompatible with all the current models, as shown by this diagram from Chapter 2 of IPCC 2013:
Comparison between the IPCC Mean Annual Global Surface Temperature Anomaly and the current IPCC climate models (IPCC 2012 Chapter 2).
Because of this failure and the fact that the IPCC Mean Annual Global Temperature anomaly has not changed for the past 17 years, they have decided to treat it on a decadal basis instead, as follows:
This irregularity is simply not compatible with a theory that it is caused by a steadily increasing concentration of ‘greenhouse gases.’
There is a much more plausible temperature anomaly record from measurements in the lower atmosphere since 1978 by Microwave Sounder Units (MSU) on NASA satellites, measuring the microwave spectrum of oxygen. Their results are confirmed by weather balloons which have been providing a record since 1958. Since 2000 all of the records are beginning to resemble one another.
They provide further evidence that IPCC models are currently incapable of predicting climate properties. These results show that IPCC figures for climate sensitivity are far too high, and the opinion of the meteorologists that its value is negligible is confirmed.
CONCLUSION
It is surely evident that the estimates of climate sensitivity given by the IPCC are grossly exaggerated. The true figure is most probably near to that which is already assumed by the weather forecast meteorologists, negligibly low. This remark would also apply to calculations published by sceptics who have accepted too readily the earlier parts of the IPCC temperature anomaly and of some of the calculations from it.
REFERENCES
D’Aleo J. and Watts. A. 2010 “Surface Temperature Records, Policy-Driven Deception”.
http://scienceandpublicpolicy.org/originals/policy_driven_deception.html
Hansen, J., & S. Lebedeff. 1987. “Global Trends of Measured Surface Air Temperature” Journal of Geophysical Research 92 13345-13372.
IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley(eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp
McKitrick, R.R. and P.J. Michaels, 2007, Quantifying the influence of anthropogenic surface processes and inhomogeneities on gridded global climate data, J. Geophys. Res. 112, D24S09, doi:10:1029/2007JD008465
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