Is Carbon Dioxide Making Our Blood Toxic?

0:00There's a new scientific claim about human-caused climate change. I know what you're thinking, isn't there always? Well, yes, but this one is especially dramatic and if it is true, potentially quite serious. Let me begin with a question. What is the most important fluid to human life? You might say it's the atmosphere. After all, we get the oxygen we need to breathe from the atmosphere. We exhale carbon dioxide into the atmosphere, which plants then use during photosynthesis. Or perhaps you would say it's the oceans. They contain vastly more mass than the atmosphere, store enormous amounts of heat, and play a major role in controlling both the Earth's energy balance and the movement of moisture through the atmosphere. Both are obviously important, and we are repeatedly told that both are being altered by greenhouse gas emissions. But according to a recent study, there's another fluid, one even more immediately important to each of us

1:01that may also be affected by rising carbon dioxide. Let's see what it is. I am David Arligates and welcome to Sanity Check, a production of the Cornwall Alliance for the Stewardship of Creation. The Cornwall Alliance is a ministry dedicated to helping fulfill the mandate God gave mankind in Genesis 128, to subdue and rule the Earth in a way that enhances its fruitfulness, its beauty, and its safety for the glory of God and for the benefit of our neighbors. Well, I won't keep you in suspense any longer. That fluid is our blood. Whether you are AB positive, O negative, or somewhere in between, the claim is that rising atmospheric carbon dioxide may already be changing our blood chemistry. The headlines certainly get your attention. A paper published in air quality, atmosphere, and health warns of a carbon dioxide overload, detected in human blood,

2:06and suggests that the atmosphere could become potentially toxic within about 50 years. That's an extraordinary claim. It suggests that sometime around 2075 atmospheric carbon dioxide could become dangerous, not simply because of its effect on climate, but because it could directly alter the chemistry of our blood. Wow. Wow. The study was conducted by two Australian researchers, a three-aid with Curtin University, the University of Western Australia, the Australian National University, and the Kids Research Institute, Australia. One is a respiratory physiologist. The other is a retired environmental geoscientist. The examine more than two decades of data from the U.S. National Health and Nutrition Examination Survey, better known as Enhanes. This large federal health survey collects medical and laboratory information from thousands of Americans.

3:08The researchers examine Venus' blood measurements from roughly 7,000 people during each two-year survey period between 1999 and 2020. They reported that average by carbonate levels in the blood increased from about 23.8 micro-equivalence per liter in 1999 to about 25.3 by 2019-2020, and increased of roughly 7%. Over approximately the same period, atmospheric carbon dioxide increased from about 369 parts per million to around 420 parts per million, and increased of roughly 14%. The researchers noted that the two trends occurred at the same time, and you can probably see where this is going. If the trend in blood by carbonate continues, they argue, average levels could reach the upper end of the normal range for healthy adults in about 50 years.

4:11They also reported declines in blood calcium and phosphorus. Some media coverage has portrayed this as a new and surprisingly personal dimension of climate change. We usually hear about heatwaves, melting glaciers, sea level rise, droughts, or hurricanes. Now the suggestion is that climate change may be reaching inside of our bodies and changing our blood. Climate change in other words has become personal. But before becoming alarmed, there are some important numbers we need to consider. Remember that average blood by carbonate increased from about 23.8 to about 25.3 micro-equivalence per liter. The normal adult reference range is approximately 22 to 29. So both the earlier and later values are comfortably within the normal range. More importantly, two things increasing at the same time does not mean that one caused the other.

5:14Statisticians have a familiar phrase for this. Correlation does not prove causation. Now to their credit, the authors acknowledge that they have not demonstrated a direct causal relationship between rising atmospheric carbon dioxide and changes in human blood chemistry. But the title of the article, Carbon Daxide Overload, detected in human blood, suggests a potentially toxic atmosphere within 50 years, certainly encourages the reader to make that connection. So the important question is this. Does a proposed connection make physiological sense? To answer that, we need to understand something about how the human body handles carbon dioxide. Your body constantly produces carbon dioxide as a product of metabolism. Every minute of every day, your cells generated. Your bloodstream carries it to your lungs and your lungs remove it when you exhale.

6:17As a result, the carbon dioxide concentration inside your body is enormously greater than the concentration in the outdoor atmosphere. The partial pressure carbon dioxide in arterial blood is normally around 40 millimeters of mercury. If expressed approximately as a gas concentration, that corresponds to about 52,000 parts per million. Think about that number for a minute. At Mr. Carbon Daxide is currently a little over 400 parts per million. Inside the body, we routinely deal with the equivalent of tens of thousands of parts per million. That is well over three-quarters of magnitude above the concentration found in outdoor air. When you inhale, some carbon dioxide does enter your lungs from the atmosphere, but the amount is tiny compared with the carbon dioxide continuously being delivered to your lungs by your own bloodstream. In other words, the carbon dioxide in your lungs is overwhelmingly controlled

7:21by your own metabolism and breathing, not by the relatively small amount of carbon dioxide in outdoor air. And God has given the human body an extraordinarily effective system for regulating it. Our respiratory control system is highly sensitive to carbon dioxide and blood acidity. If carbon dioxide in arterial blood begins to rise, even slightly, breathing adjusts. We ventilate a little more and exhale the excess carbon dioxide. Over longer periods, the kidneys provide another level of regulation by adjusting by carbon levels to keep the blood acidity within a remarkably narrow range. This is important because carbon dioxide dissolved in water forms carbonic acid. Changes in carbon dioxide, therefore, can affect blood pH. That is precisely why the body regulates carbon dioxide so carefully. Now consider the actual increase in atmospheric carbon dioxide. Since the late 1990s,

8:27atmospheric concentrations have increased by roughly 50 parts per million. Simple physiological calculations indicate that an increase of that magnitude would alter carbon dioxide pressure in the lungs and arteries by only about 0.03 millimeters of mercury. That is extraordinarily small and that presents a serious problem for the hypothesis. A change that small is nowhere near large enough to explain an increase of roughly 1 to 1.5 micro-equivalence per liter in blood by carbonate through the normal chemistry governing carbon dioxide by carbonate and blood pH. A 2024 analysis in active physiologica by multi-in-colleges made essentially this argument. Even under scenarios involving substantially higher future atmospheric carbon dioxide, the body's respiratory and kidney systems should have ample capacity and maintain normal acid-based balance. In other words, the proposed mechanism does not appear

9:34to scale properly. It is certainly true that chronically elevated carbonate oxide in the blood can increase by carbonate. Physicians see this in people with certain respiratory disorders. For example, someone who chronically does not breathe deeply or frequently enough may retain carbon dioxide. Certain lung diseases and obesity hypoventilation syndrome can produce this condition known as hypercapnia. But in those cases, arterial carbon dioxide actually rises substantially. That is completely different from increasing outdoor carbon dioxide by a few dozen parts per million. The two situations simply are not in the same ballpark. And that brings us to a second major problem with the study. It is observational. The researchers examined average blood chemistry during successive enhanes survey periods and compared those averages with rising atmospheric

10:35carbon dioxide. They observed that by carbonate generally rose while atmospheric carbon dioxide rose. But there are many other things that changed in the American population between 1999 and 2020. Diet changed. Obesity rates changed. Medication used changed. The prevalence of chronic diseases changed. The age and health characteristics of the population changed. And all of these can potentially influence blood chemistry. Dietary acid load, for example, can affect by carbonate. Dias containing relatively more animal protein and fewer fruits and vegetables can be associated with somewhat lowered by carbonate levels. Kidney function is also important because the kidneys play a central role in regulating by carbonate. Kidney functions change with age and disease. Medication such as diuretics can alter electrolytes and pH balance. Obesity

11:39and chronic lung diseases such as COPD can affect respiration and carbon dioxide regulation. Even laboratory procedures and measurement techniques can change slightly over decades. These potential influences make it very difficult to look at two population trends and conclude that one caused the other. There is another clue in the data itself. Amospheric carbon dioxide is increased rather steadily. The blood by carbonate measurements have not. The biological data contain dips, plateaus and year-to-year variation. If atmosphere carbon dioxide were the dominant factor controlling the blood chemistry trend, we might expect a clearer relationship. Then there is a prediction that the atmosphere could become potentially toxic within 50 years. That prediction depends on extending the observed trend forward in essentially a straight line.

12:43The biological systems rarely behave that simply. The authors project that averaged by carbonate could eventually approach about 29 micro-equivalence per liter, the upper end of today's commonly used reference range. But a reference range is not a boundary between safe and toxic. It is primarily a statistical description of values commonly observed in a healthy population. A population average that moves somewhat closer to one end of a reference range does not automatically mean that people are being poisoned. And extending a relatively short observational trend many decades into the future assumes that everything continues changing at the same rate. Those are very large assumptions. Human physiology is dynamic, breathing adjusts. Kidney function regulates by carbonate. The body continually responds to changes in its internal chemistry. There is also an important matter of

13:48scale. Experimental studies that demonstrate clear physiological effects from breathing elevated carbon dioxide generally expose people to concentrations measured in the thousands of parts per million, not merely a few hundred. Those concentrations can occur in enclosed indoor environments where occupational settings where ventilation is inadequate. Subrines, for example, can operate with carbon dioxide concentrations far above normal outdoor levels, sometimes in the range of several thousand parts per million, although exposure limits depend on concentration and duration. That does not mean very high carbon dioxide concentrations are harmless. At sufficiently high levels, carbon dioxide unquestionably can become dangerous, but concentration and duration matter enormously. A toxic effect observed at several thousand or tens of thousands of parts per million

14:51cannot simply be assumed to occur at a few hundred parts per million. The respiratory and renal systems God gave us can regulate carbon dioxide across a substantial range of conditions, the claim that modern atmospheric carbon dioxide has already moved humanity beyond its ability to adapt physiologically remains a hypothesis and not a demonstrated fact. None of this, however, means the changes observed in the N-haines data are uninteresting, quite the opposite. If average by carbonate really has increased, while calcium and phosphorus have declined, scientists should investigate why. Perhaps changes in diet are involved. Perhaps medication use plays a role. Perhaps obesity, kidney function, respiratory disease, demographics, where other environmental influences contribute. Those are legitimate scientific questions. It is also perfectly reasonable to examine

15:54whether changes in atmosphere composition play some role. But that is very different from concluding that rising outdoor carbon dioxide is already changing human blood chemistry and putting us on a path towards a toxic atmosphere. The study finds a correlation, but it does not demonstrate causation. So the takeaway is fairly straightforward. Science often begins by noticing correlations. That is entirely appropriate. Correlations can provide clues that lead to important discoveries, but a correlation is only the beginning of an investigation, and not the end of one. The interesting observation here is that some measures of blood chemistry changed during approximately the same period that atmospheric carbon dioxide increased. The much stronger claim that atmospheric carbon dioxide caused those changes and may produce a toxic atmosphere within

16:5650 years requires considerably more evidence. But based on what we currently understand about respiratory physiology, acid-based chemistry, and the actual concentrations involved, it is a hypothesis that does not yet survive close scrutiny. Thank you for listening to Sanity Check, a production of the Cornwall Alliance for the Storage Ship of Creation, a nonprofit ministry supported by donations from individuals like you. To support us, you can donate at CornwallAlliance.org-donate. That's CornwallAlliance.org-donate. And until next time, I am David Arley Gates, and may the Lord of all creation riftly bless you.