Global Warming: CO2 vs Sun

Abstract

It is an undoubted fact, within the scientific community, that the global temperature has increased by about 0.7°C over the last century, a figure that is considered disproportionally large. With the whole world being alarmed, the scientific community has assumed the task to explain this warming phenomenon. This has resulted in the formation of basically two schools of thought with two opposing theories. The first theory (the most popular one) claims that the prime guilty for the recent temperature increase is the release of greenhouse gases – mainly Carbon Dioxide (CO2) – coming mostly from the burning of fossil fuels, the clearing of land and the manufacture of cement. Due to these anthropogenic activities the concentration of CO2 has increased by about 35% from its ‘pre-industrial’ values, with all the resulting consequences. There are though other factors – besides the greenhouse gases – that affect the global temperature, like changes in solar activity, cloud cover, ocean circulation and others. Therefore, the ‘second’ theory claims that it is the Sun’s activity that has caused the recent warming that, incidentally in this theory, is considered to be in the generally expected limits of the physical temperature variation throughout the aeons. One assumption on how the Sun is affecting the climate is that the magnetic field and the solar wind modulate the amount of high energy cosmic radiation that the earth receives. This in turn affects the low altitude cloud cover and the amount of water vapor in the atmosphere and thus regulates the climate. (It must be noted that water vapor is considered as the main greenhouse gas.) In the sequel both of the above-mentioned theories are examined and conclusions about their soundness are drawn. Firstly (section 2), an analysis in past time of the temperature of the Earth is presented, showing that today’s temperatures are not in any way extraordinary, unnatural or exceptional, contrary to what many scientists claim. In fact, on large time scale today’s temperatures agree with what was expected for this geologic period, while on a small time scale the higher temperatures observed are the result of a natural recovery of the planet from the global coldness of the Little Ice age. In section 3, the view of the Intergovernmental Panel on Climate Change (IPCC) on the effect of the accumulation of the CO2 in the atmosphere is presented. Then, in section 4 the CO2 accumulation effect during the past is examined on large and small time scales. Note that Florides & Christodoulides (2009) using three independent sets of data (collected from ice-cores and Chemistry) presented a specific regression analysis and concluded that forecasts about the correlation between CO2-concentration and temperature rely heavily on the choice of data used, making it very doubtful if such a correlation exists or even, if