The picture of global temperature and its drivers as presented by the IPCC and the computer climate models is one in which CO2 has been the dominant factor since the start of the industrial age and other factors have had minimal impact. In order to support this picture, the IPCC has sought to portray CO2 as having been an important driver of global temperature in the past.
The idea that CO2 has been an important driver of global temperature is not supported by the evidence from the MWP and LIA (905 to 1977).
It is important to recognise that the formulae used here represent the internal workings of the climate models. There is no “climate denial” here, because the whole series of articles is based on the premise that the climate computer models are correct, using the mid-range ECS of 3.2.
Guest essay by Mike Jonas
This article is the second in a series of four articles.
Part 1 of the series (Part 1) is here
In Part 1, simple mathematical formulae were developed to emulate the carbon dioxide (CO2.) contribution to global temperature change, as represented in the computer climate models.
This article uses the formulae to have a look at the Medieval Warming Period (MWP) and Little Ice Age (LIA).
Note : This article does not say anything new, or claim to find any new results. It has all been said many times before. But by using simple formulae that emulate the internal workings of the computer climate models, it allows the CO2 and non-CO2 components of global temperature change to be quantified using a spreadsheet  instead of a sophisticated climate model.
Please note : In this article, all temperatures referred to are deg C anomalies unless…
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