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04.22.2026

The CO2 Problem: Climate Models vs. Field Measurements

G. Shanmugam

Department of Earth and Environmental Sciences

The University of Texas at Arlington, Arlington, Texas 76019, USA

ABSTRACT:

Developed countries (e.g., USA, Germany, and France) have the unfair advantage over developing countries (e.g., Republic of the Congo, Republic of Kenya, and Sri Lanka) in imposing climate rules that enforce the use of expensive renewable energy based on flawed climate models with inflated CO2 concentrations. This review attempts to bring attention to this irregular practice by amassing empirical data from field measurements on CO2 that contradict climate models. The content is presented in two parts, (1) the “PhanDA” model and (2) the CO2─1,000 ppm limit.

The “PhanDA” model-derived CO2 value by Judd et al. (2024) for the Present is ~220 ppm, which does not match the measured value of 420 ppm at the Mauna Loa Observatory in Hawaii for the Present in the Keeling Curve. During the past 50 years, the Keeling Curve shows a rapidly increasing CO2 trend, whereas the PhanDA model shows a rapidly decreasing trend.

Equally important, the PhanDA model is inapplicable for the Mesozoic era ((252 Ma-66 Ma), which represents 35% of the Phanerozoic eon (539 Ma-0). There is no correlation between Temperature and CO2 during the Mesozoic, which is the underpinning of the model. Therefore, the PhanDA model and the associated assertion on the importance of CO2 on Climate Change are problematic.

During a Trump-Musk Conversation on X (2024), Elon Musk claimed that when Atmospheric CO2 goes past 1,000 ppm from the current value of nearly 400 ppm at a rate of 2 ppm per year increase, it would cause headaches and nausea in humans. This is a consequential claim to human health. In addressing this vital issue, a rigorous examination of 80,302 empirical data points from 25 countries on CO2 concentration values available from direct measurements and from publications related to classrooms, conference rooms, dwellings, and aircraft cabins was carried out. This robust dataset (i.e., 46 figures and 13 tables) suggests that humans are able to function normally without adverse health effects even when CO2 concentration levels reach between 2,000 and 6,000 ppm. Further, the U.S. Government (USDA, 2024) does not consider the CO2─1,000 6limit as a health threat. In fact, the CO2 5,000 ppm is the U.S. Government’s Permissible Exposure Limit (PEL) of the daily workplace exposure. For basic physiological reasons, the concentration of CO2 in ambient air is almost irrelevant as long as it is much smaller than about 40,000 ppm, where it is in equilibrium with the optimum CO2 concentration of human blood. According to NRC (2007), 20,000 ppm is an appropriate sub chronic NOAEL (No Observed Adverse Effect Level) for headaches. Therefore, the notion that headaches supposedly associated with the 1.000 ppm limit of CO2 is a fallacy. There is no need for concern about indoor CO2 levels in classrooms, conference rooms, dwellings, and aircraft cabins.

Download the full article using the link: Shanmugam 2024 Keynote IAS Mag CO2 Problem published

4.20.2026

The Peer-Review Problem: A Sedimentological Perspective

JOURNAL INDIAN ASSOCIATION OF SEDIMENTOLOGISTS ISSN NO 2582 – 2020 Vol. 39, Issue 1, 2022, pp. 3-24 DOI: https://doi.org/10.51710/jias.v39i1.243 The Peer-Review Problem: a sedimentological perspective Abstract: Albert Einstein, one of the greatest physicists of all time, had a deep disdain for peer review. The peer-review process, introduced over a thousand years ago in Syria and… Continue Reading
4.10.2026

Open Letter to Federal Judicial Center Chair, Chief Justice John Roberts

Richard Lindzen, Ph. D. Professor of Earth, Atmospheric, and Planetary Sciences, Emeritus Professor of Physics Massachusetts Institute of Technology William Happer, Ph. D. Emeritus Professor of Physics, Princeton University Steven Koonin, Ph. D. Edward Teller Senior Fellow Hoover Institution, Stanford University   April 1, 2026 The Honorable John G. Roberts Chair, Federal Judicial Center Chief… Continue Reading

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