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An introduction is presented in which the authors discuss various reports within the issue on topics including average global temperatures, climate change, and General Circulation Models (GCM).

The Intergovernmental Panel on Climate Change (IPCC) has accepted that output from the Hadley Center transient climate model is 'evidence' that man-made global warming is occurring. This paper explains thatthe model output only indicates that the Hadley Center climate modeldoes not emulate climate changes in the real world. The IPCC and theHadley Center have presented the GCM model's input data as being itsoutput. This proclamation is not true and contravenes the principle of science that hypothesis are tested against observed data. [ABSTRACT FROM AUTHOR]

IPCC (2013) replaces climate models' over-predictions of near-term global warming with its "expert assessment" that warming in the next 30 years may scarcely exceed that of the last 30. Medium-term anthropogenic forcings and global temperature projections have been all but halved since 1990. There has been no global warming this millennium. Nevertheless, at the intergovernmental level, an aprioristic approach to modeling, over-confidence in models' predictive skill, and serial misrepresentation of results has prevented agreement on what fraction of recent warming was anthropogenic, how much warming we may cause and at what risk or net welfare loss, if any. The cost of mitigating predicted warming exceeds that of later adaptation by 1-2 orders of magnitude. Given governments' pre-existing monopsony of climatology, the question arises whether intergovernmental science is either necessary or desirable. [ABSTRACT FROM AUTHOR]

Observed trends in global surface air temperature depart significantly from those predicted by the ensemble of models used in the Fifth Assessment Report of the United Nations' Intergovernmental Panel on Climate Change. An alternative paradigm, where lower rates of warming are predicted, has emerged in the last three years. Here we test the hypotheses put forth by those models and document the alternative that is likely more consistent with observations. [ABSTRACT FROM AUTHOR]

Current state-of-the-art General Circulation Models (GCMs) do not simulate precipitation well because they do not include the full range of precipitation-forming mechanisms that occur in the real world. It is demonstrated here that the impact of these errors are not trivial - an error of only 1 mm in simulating liquid rainfall is equivalent to the energy required to heat the entire troposphere by 0.3°C. Given that models exhibit differences between the observed and modeled precipitation that often exceed 1 mm day-1, this lost energy is not trivial. Thus, models and their prognostications are largely unreliable. [ABSTRACT FROM AUTHOR]

General Circulation Climate Models are based on non-linear partial differential equations and therefore exhibit chaotic characteristics. Each run leads to a different temperature trend value, depending on the exact initial conditions. Modelers therefore constrain the trend value by producing an "ensemble-mean" of several runs. We show here that at least 16 runs of 25-year length are necessary to achieve convergence - and at least 4 runs of 100-year length. Contrary to expectations, we find that these numbers do not depend on the magnitude of radiative forcing of the GCM. [ABSTRACT FROM AUTHOR]

Consistency or lack thereof between observed temperature trends and those predicted by Global Circulation Models (GCMs) are a contentious though important issue. The lack of consistency between observed and modeled temperature trends has frequently been used to argue against a significant human contribution to global warming - and vice versa. We present here additional and independent evidence that there is no agreement between observed and modeled warming trends in the tropical troposphere during the last two decades of the 20th century. This finding is shown to put constraints on surface trend and Climate Sensitivity, limiting them to values close to zero. [ABSTRACT FROM AUTHOR]