"In his book "Unsettled," Steven Koonin identifies numerous deficiencies in the IPCC process that need to be addressed its finding are used for public policy.
Among the more serious deficiencies Koonin discusses are:
A) a confusion in scale between Celsius and Kelvin when estimating the influence of doubling carbon dioxide resulting in significant error, and
B) IPCC models do not track the warming trend in the surface temperature record between 1910 and 1940.
Koonin also points out the complexity of the climate models, which divide the surface and the atmosphere into various hypothetical boxes called cells.
Accurate measurements are needed for all the cells, but the measurements don’t exist.
Further, the cells are so large that important weather events may be missed.
Most important, the IPCC conclusions are political not scientific:
“And—a very key point—the IPCC’s ‘Summaries for Policymakers’ are heavily influenced, if not written, by governments that have interests in promoting particular policies.
In short, there are many opportunities to corrupt the objectivity of the process and product.”
A book by Japanese climatologist and former NASA researcher Mototaka Nakamura shows the deficiencies in Earth’s surface temperatures and considers them unreliable before 1980.
A quasi-global observation system has been operating only for 40 years or so since the advent of artificial satellite observation.
Temperature data before then were collected over extremely small (with respect to the Earth' s entire surface area) areas and, thus, have severe spatial bias.
We have an inadequate amount of data to calculate the global mean surface temperature trend for the pre-satellite period.
This severe spatial bias in reality casts a major uncertainty over the meaningfulness of "the global mean surface temperature trend" before 1980. [EN 7]
Nakamura also discusses efforts to discredit his views which failed.
Unlike Koonin, who accepts global mean surface temperature trends before 1980, Nakamura states these trends are highly questionable.
For example, for over 2,000 years changes in land use, such as draining wetlands, clearing forests, irrigation, urbanization, etc., have been recognized to change local climate temperatures.
Nakamura states that global surface temperature trends are based on a few, highly localized measurements, and the entire record on which global climate models are based may be highly biased.
Indeed, when comparing the results of global climate models to what is occurring in the atmosphere, where the greenhouse effect occurs,
the models are highly biased in overestimating the warming effect of carbon dioxide and other greenhouse gases.
Both authors express major difficulties in the approach used by the UN IPCC and US government in assessing the effect of greenhouse gases.
The atmospheric temperature effects of greenhouse gases are far less than what the models show.
Christy, et al., compared four different satellite datasets, four different weather balloon datasets, and four sets of weather reanalyzes with the average of model simulations used in the Fifth Assessment Report of the IPCC.
The researchers found the models grossly overestimate actual atmospheric temperature trends and that the disparity is increasing.
Global climate models may be useful teaching tools, but they are not useful for government policy on greenhouse gases. [EN 8]"