The Simple Science of Climate Change

The critics of the science of global climate change act as if climatology and the science if global climate change are somehow complicated, obscure, or esoteric. They also act as if it is a new-fangled theory, dreamed up by modern day Luddites. Both are simply not true.

The science of climate change is very basic, very simple. Most people have personal experience with the underlying science behind “global warming.” Most of us have done a simple science experiment, probably in high school, where we added salt into water and noted that it changes the freezing point. The basic idea is that an impurity in a solution changes the physical properties of the solution. Adding salt to water changes the freezing point.

Air is a gaseous solution of nitrogen, oxygen, argon and some trace elements. There is also gaseous – or vaporous – water in the air. Changes in these elements, or in other impurities in the air, change the physical properties of the air, particularly its ability to retain heat.

Believe it or not, must people have first-hand experience with this phenomena. Humidity, which is the measure of water vapor in air, changes the ability of air to retain heat. Most everyone knows this. The humidity in the air is why it typically stays warm at night in the summer. If, for example, it gets up to 86 degrees on a humid summer day, it might only cool off to the low 70’s at night. But if it gets up to the same 86 degrees on an early fall day, a day with low humidity, it may cool off into the 50’s at night. Anyone who has spent time in the desert has also experienced this effect. It may get into the 90’s or 100’s during the day, but it often cools down into the 40’s and 50’s at night. Places in the tropics, where the humidity is high, may also reach the upper 90’s during the day, but only cool into the low 80’s at night. The reason is that the water vapor in the air helps the air retain heat, or in the case of the desert, the lack of moisture in the air allows the air to cool quickly once the sun is down.

This is part of what is known as the greenhouse effect. The idea was first developed by the French scientist Joseph Fourier in the 1820’s. A British scientist named John Tyndall did studies in the 1850’s that helped explain why water vapor in the atmosphere held heat. He also said that other impurities in the air, including carbon, could help the atmosphere retain heat. Finally a Swedish scientist named Svante Arrhenius put it all together in what is now known as the “Greenhouse effect”. There are two components to the Greenhouse Effect. One component is that the impurities in the air alter the heat retention properties of the air, and the other component is that the impurities in the air alter the ability of the atmosphere to block infrared radiation emanating from the planet. So humidity allows the air to retain heat. Arrhenius did his work in the later early 1900’s.

Arrhenius also noted that increases in carbon dioxide in the atmosphere would cause the atmosphere to retain heat. Arrhenius actually thought that heating the atmosphere would be a good thing, and would help prevent a new ice age which might destabilize humanity. In a book called “Worlds in the Making” published in English in 1908 he said that if “the quantity of carbonic acid [CO2] in the air should sink to one-half its present percentage, the temperature would fall by about 4°; a diminution to one-quarter would reduce the temperature by 8°. On the other hand, any doubling of the percentage of carbon dioxide in the air would raise the temperature of the earth’s surface by 4°; and if the carbon dioxide were increased fourfold, the temperature would rise by 8°.” (p53) [See, e.g. the American Institute of Physics, which has an excellent history of the science behind Global Climate Change at:]

His numbers were off for a number of reasons, including the ability of the oceans to absorb carbon dioxide, but his description of the basic science of global warming, or climate change, was dead on. Raising the amount of carbon dioxide (and other carbon based impurities) in the atmosphere alters the ability of the atmosphere to retain heat and causes the atmosphere, and the planet as a whole, to heat up.

This has been the dominant model of climatology ever since (with a brief foray into global cooling, as discussed below). So we have known for well over 100 years that adding carbon to the atmosphere would warm the planet. The terminology changed recently because it was clear that the impact was not simply warming. The additional heat in the atmosphere manifests itself in disruption of normal weather patterns, and can result, as it did the past winter, in unusually cold temperatures in some regions. So now we use the more accurate terminology of “climate change” but the scientific principles remain the same. They are simple, and well established scientific principles, and they are principles that have been around for over 100 years.