A Swiss scientist known to have published hundreds of scientific papers in physics journals has authored a new scholarly paper that casts serious doubts on the effectiveness of CO2 as a greenhouse gas influencing Earth’s temperatures.
This paper has been added to a growing volume of peer-reviewed scientific papers that seriously question estimates of a high climate sensitivity to significant increases in CO2 concentrations.
The link above contains a compilation of over 60 scientific papers with “extremely low” (numerically ranging from 0.02°C to <1°C) estimates of the climate’s sensitivity to a 100% increase in CO2 concentrations (i.e., an increase from 285 ppm to 570 ppm).
Below are some of the key user-friendly (non-technical) points from Dr. Reinhart’s paper entitled Infrared absorption of atmospheric carbon dioxide.
A summarizing conclusion from the calculations may be that if we doubled today’s concentration (400 ppm) to 800 ppm, the consequent temperature response would be less than 1/4th of a degree Celsius. Even with a ten-fold increase in today’s CO2 concentration (400 ppm) to 4,000 ppm, the resulting temperature change would amount to just 0.8°C.
Over 200,000 discrete absorption lines of CO2 are used for the numerical calculations. If the absorbed energy is converted entirely into heat, we deliberately overestimate the heat retention capability of CO2. The thermal occupation statistics of the CO2 energy states play a key role in these calculations. The calculated heat retention is converted into a temperature increase, ∆T. Doubling the present CO2 concentration only results in ∆T [temperature increase of] < 0.24 K. At the present rate of CO2 concentration increase of 1.2% per year, it will take almost two hundred years to reach ten times the present concentration yielding ∆T < 0.80 K.
CO2 ‘Very Weak’, IPCC Assumptions ‘Violate Reality’
Based on all these facts, we conclude that CO2 is a very weak greenhouse gas. We emphasize that our simplifying assumptions are by no means trying to minimize the absorption potential of CO2. To the contrary, they lead to overestimating the limiting values. The assumption of a constant temperature and black body radiation definitely violates reality and even the principles of thermodynamics.
[W]e conclude that the temperature increases predicted by the IPCC AR5 lack robust scientific justification. The main problem is probably caused by the lack of considering the occupation probabilities of the energy levels.
Temperature Changes In Response To Large CO2 Concentrations (800 ppm – 4,000 ppm)
We have calculated ∆Fmax and ∆Tmax for four concentrations namely 400 ppm, 800 ppm, 2000 ppm and 4000 ppm. The results are listed in Table I. They can be quite accurately fitted with logarithmic concentration dependence.
A doubling [to 800 ppm] of the present level of CO2 [400 ppm] results in ∆T [temperature change] < 0.24 K.
The tenfold value of [the present CO2 concentration, or 4,000 ppm] yields ∆T [temperature change] < 0.80 K.
At pre-industrial times, we had cco2 = 285 ppm. The resulting temperature increase [since pre-industrial] according to Eq. (11) only amounts to ∆T < 0.12 K.
Solar Activity Correlates With Temperature, Non-Positive Feedbacks
Lu [and co-authors, 2013] establishes a correlation of ∆T with solar activity, cosmic rays and ozone reactions with fluorocarbons in the stratosphere. According to his result, CO2 only plays a minor role in the temperature evolution since pre-industrial times. Our calculation is compatible with his finding.
There remains the question of the existence of feedback. This effect is thought to amplify or attenuate a small temperature change. Such mechanisms are easy to imagine, but they are extremely difficult to quantify and to observe. Lindzen has tried to observe feedback by complicated correlation studies. He found a tendency to negative feedback that attenuates induced temperature changes because, in this perspective, the weak CO2 concentration effect is not magnified.
Our results permit to conclude that CO2 is a very weak greenhouse gas and cannot be accepted as the main driver of climate change. The observed temperature increase since pre-industrial times is close to an order of magnitude higher than that attributable to CO2. We find that the increase of CO2 only might become dangerous if the concentrations are considerably greater than 4000 ppm. At present rates of increase, this would take more than 200 years. Therefore, demands for sequestering CO2 are unjustified and trading of CO2 certificates is an economic absurdity. The climate change must have a very different origin and the scientific community must look for causes of climate change that can be solidly based on physics and chemistry.
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