Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Atmospheric Temperature and CO2: Hen-or-Egg Causality?

Version 1 : Received: 7 September 2020 / Approved: 11 September 2020 / Online: 14 September 2020 (00:00:00 CEST)
Version 2 : Received: 7 September 2020 / Approved: 11 September 2020 / Online: 20 October 2020 (00:00:00 CEST)

A peer-reviewed article of this Preprint also exists.

Koutsoyiannis, D.; Kundzewicz, Z.W. Atmospheric Temperature and CO2: Hen-Or-Egg Causality? Sci 2020, 2, 83. Koutsoyiannis, D.; Kundzewicz, Z.W. Atmospheric Temperature and CO2: Hen-Or-Egg Causality? Sci 2020, 2, 83.

Abstract

It is common knowledge that increasing CO2 concentration plays a major role in enhancement of the greenhouse effect and contributes to global warming. The purpose of this study is to complement the conventional and established theory that increased CO2 concentration due to human emissions causes an increase of temperature, by considering the reverse causality. Since increased temperature causes an increase in CO2 concentration, the relationship of atmospheric CO2 and temperature may qualify as belonging to the category of “hen-or-egg” problems, where it is not always clear which of two interrelated events is the cause and which the effect. We examine the relationship of global temperature and atmospheric carbon dioxide concentration at the monthly time step, covering the time interval 1980–2019, in which reliable instrumental measurements are available. While both causality directions exist, the results of our study support the hypothesis that the dominant direction is T → CO2. Changes in CO2 follow changes in T by about six months on a monthly scale, or about one year on an annual scale. We attempt to interpret this mechanism by involving biochemical reactions, as at higher temperatures soil respiration, and hence CO2 emission, are increasing.

Keywords

temperature; global warming; greenhouse gases; atmospheric CO2 concentration

Subject

Environmental and Earth Sciences, Environmental Science

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