Is climate change real? If so, what is the cause? Is it caused by human activity? And can it be reversed? If so, should it be reversed? Many people have never stopped to consider these questions because they think they already know the answers to all of them. After all, we have been told that climate change is real, dangerous, caused by human activity, and that we should fight it by reducing our carbon footprint. But does science bear out such claims? Most importantly, what does the Bible teach on this topic?
“Climate” refers to the general meteorological conditions of a region averaged over a period of many years. Such conditions include temperature, humidity, precipitation, wind, and sunshine. Such conditions at any given moment are simply referred to as weather. The weather of a given region varies from day to day, and even somewhat from year to year. But over a period of many years, the average of all meteorological conditions is the climate. If such conditions change substantially over a period of many years or centuries, then this is referred to as climate change.
Past Examples
In the past, there have been periods of substantial climate change. Geological evidence indicates that Earth’s climate was quite different before the global flood. Furthermore, there is compelling evidence that the Earth experienced an ice age after (and as a result of) the global flood. This ice age lasted several centuries, during which the global climate was quite different from what it is today.
There are at least two other examples of climate change after the ice age, but these are much less extreme. One is known as the Medieval Warm Period. This happened roughly between A.D. 950 and A.D. 1250, during which the North Atlantic region was substantially warmer than it is today. This led to increased crop yields in Europe. Wheat and grapes could be grown at latitudes far higher than today.
Another example of climate change is called the Little Ice Age which peaked in the mid-1600s. During this period, year-averaged temperatures in Europe were colder than today by around two degrees. This resulted in reduced harvests and consequently famines. This period was marked by dramatic advances of glaciers. The Little Ice Age prevailed until around 1850. A few other possible examples of climate change in the past have also been identified. Whether these changes in climate were global in extent or regional is debated. But they demonstrate that climate change does happen.
Climate Change Today
Many people today are very concerned about global warming and the possible consequences of a much warmer planet in the near future. But these kinds of concerns are not new. In the 1970s many people were worried about global cooling and the possibility of another little ice age to come. Indeed, an April 28, 1975, article in Newsweek entitled “The Cooling World” made compelling arguments that the Earth’s average global temperature had been cooling for decades and that this trend might continue. Many other publications also supported the possibility of a much colder Earth in the near future and the resulting famine that would inevitably follow. Of course, this didn’t happen. And today, many climatologists argue that such a position was never really warranted by the evidence. But people believed it at the time. This is just one reason why we should be cautious about jumping to alarmist conclusions about something as complex as climate change.
Nonetheless, modern temperature estimates suggest that Earth’s average global temperature has risen over the last century by approximately one degree Celsius as indicated in the NASA graph below.
Assuming these measurements are accurate, then global warming in the past century has been quite small. Temperatures today are considerably lower than they were during the Medieval Warm Period – a time of high crop yield. Indeed, global warming – if it happens – would save lives not only by increasing food production but by reducing deaths from exposure. In a given year, far fewer people die from exposure to heat than from exposure to cold.
Then again, perhaps the concern is that global warming will run away to such an extreme that it would result in the planet being uninhabitable, like Venus. Venus has a thick atmosphere of carbon dioxide which causes its surface temperature to be around 900 degrees Fahrenheit. Could something like that possibly happen on Earth? In order to answer this question, we need to understand what factors control Earth’s temperature.
The Greenhouse Effect
Most people have directly experienced the greenhouse effect in their own vehicle. When a vehicle has been parked in sunlight for a long period of time with the windows up, the temperature inside the vehicle is noticeably hotter than the temperature outside. This is because glass windows allow visible light to pass but trap heat. Sunlight passes through the windows of the vehicle and strikes the interior surfaces. Some of that light is reflected away, but the rest is absorbed by the surfaces which increases the randomized velocities of their atoms. This increase in kinetic energy we call temperature. Hot surfaces emit infrared radiation which would normally travel back out of the vehicle, cooling the surfaces. But glass is mostly opaque to infrared radiation and, therefore, redirects the heat back into the vehicle.
Certain gases in the Earth’s atmosphere do the same thing – these are greenhouse gases. As one example, carbon dioxide is transparent to visible light but traps heat much the way glass does. Thus, Earth’s surface is hotter than it would be without any greenhouse gases. And this is a good thing. Without any greenhouse effect, the Earth’s average temperature would drop from its current comfortable 57 degrees Fahrenheit to around 0 degrees Fahrenheit. Life could not survive on Earth without the greenhouse effect.
The most common assumption for the apparent one-degree increase in Earth’s average temperature over the last century is an increase in atmospheric carbon dioxide as a result of human industry. The burning of fossils fuels, whether in gasoline engines or coal-powered electric plants, releases carbon dioxide into the atmosphere. And since both industrial carbon dioxide production and global temperatures have increased in the past century, the common assumption is that the former is the cause of the latter. This is a possibility, but there are several things to consider before jumping to this conclusion.
First, the correlation is not as strong as is often assumed – particularly on a short-term timescale. For example, there was a noticeable and temporary increase in Earth’s global temperature in both the late 1800s and the early 1940s. But manmade carbon dioxide emissions were not high during these periods. At the very least, this shows that manmade carbon dioxide emissions are not the only factor in climate change.
Second, correlation does not prove causation. In other words, although there is a general trend that high atmospheric carbon dioxide levels correlate with higher temperatures, we cannot automatically assume that the former causes the latter. We know that, at least to some extent, the reverse is true. That is, higher temperatures cause the atmospheric carbon dioxide to rise. This is because Earth’s oceans contain a great deal of dissolved carbon dioxide. And colder water can hold more carbon dioxide that hotter water. Thus, when the ocean warms, it releases carbon dioxide into the atmosphere. Then when the ocean cools, it reabsorbs atmospheric carbon dioxide. It may be the temperature that primarily drives atmospheric carbon dioxide levels rather than the reverse.
Third, the medieval warm period had temperatures higher than those of today, yet there was no human industry at that time. And likewise, the little ice age could not have been caused by a reduction of human industry since its peak occurred before any human industry. These examples of climate change prove beyond all doubt that climate undergoes natural cycles that have nothing whatsoever to do with manmade carbon dioxide emissions.
Fourth, less than one third of atmospheric carbon dioxide can be attributed to human activity. There are many natural sources of carbon dioxide. The ocean is the single largest source. Volcanos release copious amounts of carbon dioxide, as do forest fires. Animal respiration releases carbon dioxide, and so does decomposition of organic matter.
Fifth, atmospheric carbon dioxide is a minor greenhouse gas in terms of its contribution. It comprises only 0.04% of Earth’s atmospheric gases. The most important greenhouse gas is actually water vapor which is responsible for about half of the Earth’s greenhouse effect. The next most important factor is clouds, which are liquid water droplets in suspension. Clouds are responsible for perhaps one fourth of the greenhouse effect but have a complex effect on Earth’s temperature because they can either increase or decrease it depending on the circumstances. At night, clouds act like any greenhouse gas, trapping heat that would otherwise escape to space. But during the day, they both trap heat and also reflect sunlight, preventing it from heating Earth’s surface in the first place. Carbon dioxide is third on the list, responsible for perhaps 20% of the greenhouse effect. The remaining greenhouse gases, like methane, nitrous oxide, and ozone, contribute only a few percent.
Sixth, the Earth has many self-regulating features which provide a negative feedback system. Such systems stabilize Earth’s temperature and prevent any runaway effect. For example, plants require carbon dioxide to grow and thereby remove carbon dioxide from the atmosphere. Thus, any increase in atmospheric carbon dioxide production should result in increased plant growth – an effect called carbon fertilization. Increased plant growth causes more carbon dioxide to be removed from the atmosphere. Indeed, researchers have documented increased plant growth in the last several decades in response to increased atmospheric carbon dioxide.[1]
Seventh, the most intense absorption bands of carbon dioxide are near saturation – meaning they are trapping essentially 100% of the infrared radiation in that wavelength range. Thus, increasing the carbon dioxide will not trap significantly more heat because it is already trapping all the heat in the relevant range. There are less intense absorption bands that are not saturated, and thus some additional heating may occur, but it will be increasingly less effective. In other words, the effect of greenhouse heating is not linearly proportional to the quantity of gas but increases asymptotically, reaching a limit. This fact alone should dissuade anyone from thinking that we are in for a climate crisis due to carbon dioxide emissions.
There are planets with a runaway greenhouse effect such as Venus. But this could never happen on Earth because the conditions are quite different. The atmosphere of Venus is nearly 100 times as massive as that of Earth. Furthermore, the atmosphere of Venus is 95% carbon dioxide, whereas Earth’s is 0.04%. To put that in perspective, Venus has nearly 200,000 times more carbon dioxide in its atmosphere than Earth. Also, Venus is 28% closer to the sun, and thus receives nearly twice as much solar energy! On the other hand, consider Mars. It actually has ten times more carbon dioxide in its atmosphere than Earth. Yet, the average surface temperature on Mars is negative 85 degrees Fahrenheit. Why hasn’t Mars experienced a runaway greenhouse effect? We still haven’t considered the most important factor in determining a planet’s temperature: the Sun.
The Sun
By far the most significant source of Earth’s energy is a G-class star conveniently located 93 million miles away: the sun. The sun has an energy output of 3.86×1026 Watts. This energy streams away in the form of light. Earth receives about 1.75×1017 Watts from the sun, or 1370 Watts per square meter. This is called the solar constant. It is the solar energy intercepted by every square meter of surface that is perpendicular to the sun. Surfaces that are not perpendicular receive less energy. This is why the tropics on Earth are warmer than the poles. It is also why we experience temperature fluctuations with the changing seasons.
The rotation axis of Earth is tilted about 23.5 degrees relative to the axis of its orbit around the sun. Thus, at certain times of the year, the northern hemisphere is tilted toward the sun and receives sunlight that is closer to perpendicular to the surface (and the sun appears higher in the sky). Also at this time, the northern hemisphere receives more than twelve hours of daylight per rotation. These effects result in higher temperatures in the northern hemisphere in spring and summer while the southern hemisphere experiences the opposite. Six months later, the Earth has orbited to the other side of the sun; thus, the northern hemisphere is now tilted away from the sun. Sunlight is less direct (the sun appears lower in the sky), and the daylight period is shorter than twelve hours. This is why we experience colder temperatures in autumn and winter.
The distance from the sun also has an effect on temperature. The Earth’s orbit is slightly elliptical, varying from a distance of 91.4 million miles from the sun in early January to 94.5 million miles in early July. Hence, Earth receives more energy from the sun in January than in July. This is the opposite of what many people expect, particularly inhabitants of the northern hemisphere who experience colder weather in January than in July. Obviously, the effect of Earth’s tilt and the seasons that result are far more influential on temperature for a given latitude on Earth than the changing distance to the sun. But the Earth – as a whole – receives about 7% more energy from the sun in January than in July.
The sun itself has cycles that slightly affect its energy output. Perhaps the most well studied is the 22-year magnetic cycle. The sun has a dipole magnetic field (a north pole and south pole) much like Earth, but it also has toroidal fields (east-west) which occasionally poke through the surface and cause sunspots. These magnetic fields interact with each other along with the sun’s differential rotation (the equator rotates in less time than the poles). This causes the dipole field to reverse charge every eleven years. A second flip eleven years later restores the original orientation – thus twenty-two years for a complete cycle. Likewise, sunspots increase in number and intensity approximately every eleven years during a period we call “solar maximum.” When this happens, the overall intensity of the sun is slightly higher than at other times. The sun puts out more energy, and the Earth receives more energy as a result. All other factors being equal, this results in warming temperatures on Earth. Of course, other factors often obscure this subtle effect.
There are larger solar variations that are not as yet understood. For example, although the 22-year sunspot cycle is quite regular, not all periods of activity are equally intense. In other words, some periods of maximum sunspots have more spots than other periods of maximum spots. In particular, there was a period of time from approximately 1645 to 1715 in which there were very few sunspots, even during solar maximum. This is called the Maunder Minimum and corresponds approximately with the peak of the Little Ice Age. Many scientists believe that lower solar intensity during the Maunder Minimum was indeed the cause of the Little Ice Age. It is also possible that an increase in solar intensity was responsible for the Medieval Warm Period. However, this is harder to establish because sunspot records are rare and imprecise before the invention of the telescope in 1608.
Could it be that small changes in solar intensity are responsible for temperature trends on Earth over the last century? Could these effects be more significant than any greenhouse effect? This is certainly worth considering. It is also possible that any potential warming trend is due to a combination of effects rather than a single cause.
Our Response
In 2022 the United States government spent $5.8 billion to deal with climate change in response to an estimated one-degree increase in temperature over the last century. Much of this was designed to reduce carbon dioxide emissions, which we have seen are not the main contributor of greenhouse warming anyway. Furthermore, we have seen past examples of climate change that had nothing to do with human industry. We have also seen that increased temperatures have had (in the past) a net positive result, leading to increased agricultural production and the preservation of human life. Indeed, there is evidence that a similar increase in crop yield is happening now.
So assuming that human industry has contributed to global warming resulting in increased food production, is this something that we should spend billions of dollars to reverse? We have seen that God designed Earth with many feedback mechanisms that compensate for changes until a new equilibrium is reached. Plants remove atmospheric carbon dioxide, and hence their increased growth is natural. Furthermore, physics shows that the effect of greenhouse gases is nonlinear with quantity and that the most intense frequency bands of carbon dioxide are near saturation. Logically, this means that a runaway/catastrophic greenhouse effect is not possible on Earth regardless of how much additional carbon dioxide we put into the atmosphere. Research is warranted. Alarmism is not.
The Bible on Climate Change
The science of climate is complicated because there are so many factors, only some of which are currently understood. Fortunately, the inerrant Word of God does touch on the topic of climate change. We will see that the Bible confirms that Earth’s climate was somewhat different in the past.
We have a great deal of scientific evidence that an ice age occurred as a result of the global flood recorded in Genesis 6-8. This ice age resulted in mild seasons and changed weather patterns, allowing lush vegetation to grow in regions that are deserts today. We believe that this ice age peaked a few hundred years after the global flood – and biblical records seem to confirm this.
For example, Abraham and Lot lived during the time we believe to be the peak of the ice age. And the Bible confirms very different climate conditions in places like Sodom and Gomorrah. These cities were located near the Dead Sea. Today, this region is a desert – arid, hot, and dry. But the Bible confirms that conditions were quite different during the life of Abraham and Lot. Indeed, the land was lush and green at the time. Genesis 13:10 states, “Lot lifted up his eyes and saw all the valley of the Jordan, that it was well watered everywhere — this was before the LORD destroyed Sodom and Gomorrah — like the garden of the LORD, like the land of Egypt as you go to Zoar.”
The Bible also has something to say about climate change in the future. Namely, although the climate may change from century to century, God has promised a certain degree of stability in nature. After the global flood God made a promise. In Genesis 8:21 God promised to never again send a global flood. But in the next verse He promised stability in the natural world: “While the earth remains, Seedtime and harvest, And cold and heat, And summer and winter, And day and night Shall not cease.”
God has promised that the seasons and the day/night cycle will continue as long as the Earth remains. He did not promise that the climate would never change. But His promise requires that the climate will never change so drastically as to eliminate seasons like summer and winter. Thus, climate change can happen, but catastrophic climate change cannot. Until Judgment Day, the Earth will never become so warm as to eliminate winter, nor so cold as to eliminate summer. We have a promise from the Almighty. Regardless of what human beings do or fail to do, God has promised stability in nature.
We should not take this as license to be irresponsible, of course. Certainly, we have an obligation to be good stewards of the Lord’s creation. That includes taking measure to prevent excessive pollution, to protect endangered species, and so on. It includes doing research on the various factors that contribute to the Earth’s climate. But it also means that such measures should not be taken to an unbiblical extreme.
Conclusion
From an examination of the science, we have seen that climate change is real and natural. It happened in the past before any human industry. There is evidence that it is happening now in a small way. It is indeed possible that carbon dioxide from human industry has contributed to increasing temperatures in the twentieth century. But such changes are very small and potentially beneficial. Furthermore, we have seen that there are many other factors at play that have nothing to do with human activity. There are feedback mechanisms whereby the Earth compensates for global changes, preventing any runaway effects. Thus, we have seen that there are good scientific reasons to reject the alarmist claims that a climate catastrophe will happen unless we do something immediately. On the contrary, we can expect increased crop production and reduced famine in the near future as a result of a very mild change in climate.
The Bible also confirms that the climate changes from time to time. And although humans may play a role, it is necessarily a small one. God is sovereign over the Earth and all its aspects. And He has promised that there will be stability in nature. Nothing we do can change that. There cannot be a climate catastrophe until God closes out human history at His second coming. Until then, we are to be responsible stewards of the Earth, secure in the comfort of God’s promises.
[1] https://www.nature.com/articles/s41467-022-33196-x