Atmospheric temperature and CO₂: Hen-or-egg causality?

D. Koutsoyiannis, and Z. W. Kundzewicz, Atmospheric temperature and CO₂: Hen-or-egg causality?, Sci, 2 (4), 83, doi:10.3390/sci2040083, 2020.



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.

PDF Full text (5365 KB)

PDF Additional material:

See also:


Full text in html of version 2 on journal's site:

Full text in pdf of version 2 on journal's site:

Review reports and replies of version 2 on journal's site:

Full text in html of version 1 on journal's site:

Full text in pdf of version 1 on journal's site:

Review reports and replies of version 1 on journal's site:

Blog discussions about this article

  1. New Study Finds Robust Statistical Probability Temperature Drives CO2 Changes, Upending ‘Scientific Perception’ by Kenneth Richard, 2020-10-05 (NoTricksZone)
  2. New Study: Strong Likelihood That Temperature Drives CO2 Changes—Reproduced #1 as #2 with comments by Kenneth Richard, 2020-10-05 (Climate Dispatch)
  3. Reproduced #1 in
  4. Reproduced #2 in
  5. Atmosfæretemperatur og CO2 by Geir Aaslid, 2020-10-11 (Klimarealistene)
  6. IPCC har förväxlat orsak och verkan, temperaturen driver luftens halt av CO₂ , 2020-10-13 (Klimatsans)
  7. Shock Study: CO2 Climate Theory Exposed During COVID Lockdown, by John O'Sullivan, 2020-10-13 (Principia Scientific)
  8. E’ nato prima l’uovo o la gallina?, by Donato Barone, 2020-10-20 (Climatemonitor)
  9. Temperature and Carbon Dioxide: Defying Alarmists, by Jack Dini, 2020-10-22 (Canada Free Press)
  10. Prima l’uovo o la gallina? 2.a parte: Una visione un po’ diversa, by Franco Zavatti, 2020-10-24 (Climatemonitor)

Our works referenced by this work:

1. D. Koutsoyiannis, On the quest for chaotic attractors in hydrological processes, Hydrological Sciences Journal, 51 (6), 1065–1091, doi:10.1623/hysj.51.6.1065, 2006.
2. D. Koutsoyiannis, H. Yao, and A. Georgakakos, Medium-range flow prediction for the Nile: a comparison of stochastic and deterministic methods, Hydrological Sciences Journal, 53 (1), 142–164, doi:10.1623/hysj.53.1.142, 2008.
3. D. Koutsoyiannis, A. Efstratiadis, N. Mamassis, and A. Christofides, On the credibility of climate predictions, Hydrological Sciences Journal, 53 (4), 671–684, doi:10.1623/hysj.53.4.671, 2008.
4. G. G. Anagnostopoulos, D. Koutsoyiannis, A. Christofides, A. Efstratiadis, and N. Mamassis, A comparison of local and aggregated climate model outputs with observed data, Hydrological Sciences Journal, 55 (7), 1094–1110, doi:10.1080/02626667.2010.513518, 2010.
5. D. Koutsoyiannis, A. Christofides, A. Efstratiadis, G. G. Anagnostopoulos, and N. Mamassis, Scientific dialogue on climate: is it giving black eyes or opening closed eyes? Reply to “A black eye for the Hydrological Sciences Journal” by D. Huard, Hydrological Sciences Journal, 56 (7), 1334–1339, doi:10.1080/02626667.2011.610759, 2011.
6. D. Koutsoyiannis, Generic and parsimonious stochastic modelling for hydrology and beyond, Hydrological Sciences Journal, 61 (2), 225–244, doi:10.1080/02626667.2015.1016950, 2016.
7. D. Tsaknias, D. Bouziotas, and D. Koutsoyiannis, Statistical comparison of observed temperature and rainfall extremes with climate model outputs in the Mediterranean region, ResearchGate, doi:10.13140/RG.2.2.11993.93281, 2016.
8. H. Tyralis, and D. Koutsoyiannis, On the prediction of persistent processes using the output of deterministic models, Hydrological Sciences Journal, 62 (13), 2083–2102, doi:10.1080/02626667.2017.1361535, 2017.
9. D. Koutsoyiannis, Time’s arrow in stochastic characterization and simulation of atmospheric and hydrological processes, Hydrological Sciences Journal, 64 (9), 1013–1037, doi:10.1080/02626667.2019.1600700, 2019.
10. D. Koutsoyiannis, Revisiting the global hydrological cycle: is it intensifying?, Hydrology and Earth System Sciences, 24, 3899–3932, doi:10.5194/hess-24-3899-2020, 2020.
11. Z. W. Kundzewicz, I. Pińskwar, and D. Koutsoyiannis, Variability of global mean annual temperature is significantly influenced by the rhythm of ocean-atmosphere oscillations, Science of the Total Environment, 747, 141256, doi:10.1016/j.scitotenv.2020.141256, 2020.

Our works that reference this work:

1. D. Koutsoyiannis, Stochastics of Hydroclimatic Extremes - A Cool Look at Risk, 330 pages, Edition 0, National Technical University of Athens, Athens, 2020.

Tagged under: Climate stochastics, Works discussed in weblogs, Most recent works, Papers initially rejected, Stochastics