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We Do Not Know What Cannot be Known

Why Future Climate Change is Unknown

By Bob DeWaay


In 1987, a man published a booklet that presented 88 reasons why Christ would return in 1988. Though many thousands were sold, the book was doomed to be wrong. Christ himself said that no one knows when he will return. In Christian theology, what we can know is revealed in the Bible. When Christ will return cannot be known. When it comes to what cannot be known, multiple reasons, evidence or collaborating authorities are worthless. What by nature cannot be known remains unknown no matter what.

I was converted to Biblical Christianity in 1971 when I was a junior student at Iowa State University studying chemical engineering. One of my last classes there before I switched to studying theology was physical chemistry. There we used differential calculus to write equations to predict where electrons would be in their orbits. That use of such calculus strained the limits of what can be validly predicted using it. It still does.

One day on the way to a chemical engineering class in the middle of winter, there were students protesting air pollution they saw as white smoke blowing across campus from our power plant. When I got to class, the professor told us that those students were protesting water vapor. When we have a clean burn of hydrocarbons, besides the release of energy, the by-products are CO2 and water. CO2 is invisible so what they saw that provoked the protest was water vapor. Over 45 years later, people are still protesting water vapor as witnessed by pictures of power plant exhaust stacks taken in the middle of winter, spewing out white “smoke:” water vapor. The captions are about air pollution.

We must distinguish, whether in Christian theology or science, between what can and cannot be known. Let’s start with what can be known about the combustion of hydrocarbons. If there are no non hydrocarbons such as nitrogen or sulfur, and there is complete combustion to eliminate unburned hydrocarbons, the exhaust will be CO2 and water, usually in the form of vapor. Neither CO2 or water vapor is air pollution. Both CO2 and water vapor are normal and necessary components of earth’s atmosphere.

In regard to concern about climate change, we know by studying the past that climate does change. Therefore to predict that climate will change is likely correct. But what we do not know is how it will change. We also cannot accurately quantify the various causes of change. One reason we cannot has to do with differential calculus. The known variables are many and influence one another in difficult or impossible to predict ways. Differential equations do not yield a number but a function. The function is used to predict where something will be over time (like a planet in orbit). No such valid equation can be made about climate without turning many known variables into constants. Typically the non-constant that interests people is CO2. There are many other variables such as particulates in the atmosphere, variation in sun activity, the interactions (fluid dynamics) of the movements of water vapor laden air with earth and sea and so many more.

What cannot be known is how much CO2 in parts per million in the atmosphere would make the climate more stable than it is. If somehow the amount of CO2 magically became constant, climate would still change in unpredictable ways. When it comes to the question of human caused climate change, we can only guess or speculate. This cannot be known with certainty.

I have studied and taught theology for the last 45 years. I have had to learn the lesson of not claiming to know what cannot be known. The man who cited all the reasons Christ would return in 1988 had to be wrong, not for lack of reasons, but because the timing of his return cannot be known. People who cite multiple reasons and authorities to support their claim to know how climate will be changed due to a change in CO2 alone make the same mistake. By making CO2 the ultimate evil we detract from dealing with what actually is pollution and should be eliminated. So to stay out of trouble, we all should remember this simple axiom: we do not know what cannot be known.

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We Do Not Know What Cannot be Known

Unless otherwise noted, all Scriptures taken from the New American Standard Bible, © Copyright 1960, 1962, 1963, 1968, 1971, 1972, 1973, 1975, 1977, 1988, 1995 The Lockman Foundation.

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