This miniseries is a layman’s explanation of the causes of Climate Change and its effects upon Global Warming.
What is Climate Change and what causes it? The answer is very simple yet extraordinarily complex. Greenhouse gases are the primary cause of Global Warming. But in order to understand this phenomenon one must first understand the scientific principles behind the Greenhouse effect. A greenhouse consists of a structure that is totally enclosed with glass. A very neat property of glass is that it allows most of the sun’s rays to penetrate through the glass, especially the long wavelength rays called infrared. These rays are the ones that make you feel hot when standing directly in sunlight. They are invisible to the eye but can be felt by our skin where the infrared light is absorbed by the skin and converted into heat which is what you feel. There is some physics going on at the atomic level that converts the sun’s infrared light into lower energy heat that is what you feel but I won’t go into that. This is very different from the UV light waves that actually cause sunburns which are shorter wavelength light rays. When they land on the earth most are absorbed by the various surfaces they encounter producing heat.
The amount of the sun’s infrared that is absorbed depends upon the color and texture of the surface on which it falls. Things that appear white or very smooth absorb less sunlight and reflect more directly back into the atmosphere and into space thus appear brighter to the eye. The same applies to infrared light. Darker surface colors and rougher surfaces absorb more sunlight and infrared light. The reason rough surfaces absorb more light is that they have more surface area to absorb light, like paper that is crinkled. You can stretch the crinkled paper out and it gets larger in area as the wrinkles flatten. Dark colors reflect less light and thus appear darker to our eyes. That is the meaning of dark, a color that absorbs more light than it reflects back into our eyes and into space.
When a surface absorbs infrared light it converts it into heat, which is also a form of infrared light but at a much longer wavelength which radiated from the surface and makes you feel warm or hot when you come near like the surface of a sidewalk or paved road exposed to the sun for hours. Some materials conduct heat better so absorb the heat into the bulk of the material if very thick and may only feel lukewarm or cool like water. Some materials may not conduct heat as well and will concentrate heat closer to the surface and feel much hotter such as concrete and radiate this heat into the air. The hotter an object is the more of this long wavelength infrared heat will be re-radiated back out of the surface and into the atmosphere.
Glass which is good at allowing the sunlight infrared to pass through it is very poor at allowing the longer wavelength infrared heat to re-radiated from the surface of materials back into the air so traps it inside the greenhouse resulting in the heating of the surrounding air which gets hotter and hotter. You can see this happen in your car. When you first open your car door after it has sat in the sun for a few hours it feels like an oven. The windows of your car act like a greenhouse glass allowing the longer infrared sunlight rays to enter the window and land on the interior surfaces of your car that absorbs it and turns it into heat which is trapped inside by the rolled up glass windows resulting in heating the air inside the car. That in essence is the Greenhouse effect.
There are gases that also have similar properties to glass. Carbon dioxide (CO2) is prominent among them. So is methane gas which is produced by decaying organic matter and is actually 40 time more potent than CO2 in trapping heat but far less abundant in our atmosphere. The more CO2 that is in our atmosphere the more heat is trapped in it. One saving grace about CO2 is that its concentration in our atmosphere is very low, far below 1%. It’s concentration is expressed in part per million (ppm). Currently it is about 400 ppm or in percentage 0.04% of the atmosphere. But this is the highest level it has been in more than a half million years and is still climbing. CO2 is quite soluble in water like in the cold carbonated beverages we consume all the time but at extremely high concentrations compared to that found in nature. Had there been little or no water on earth this would be a rather lifeless planet many hundreds of degrees hotter than it is due to the much higher concentrations of CO2 even if it were only 5-10% of the atmosphere. But the sheer vastness of our oceans, lakes, and clouds provide gargantuan reservoirs of water in which CO2 can be absorbed. So CO2 levels are kept quite low and greenhouse warming limited. But the ability of water to absorb CO2 depends upon how cool it is. Just like your carbonated beverage, the warmer our waters becomes the more CO2 it releases and the less can be absorbed and retain. So the amount of CO2 that is in our atmosphere depends upon how cool the waters of the oceans, lakes, and clouds can be maintained. Since water at the bottom of our oceans is much colder than at the surface the level of CO2 is far greater at deeper depths.
Links to this Miniseries:-
- Climate Change: Part 1 – The Fundamentals
- Climate Change: Part 2 – Greenhouse Gases
- Climate Change: Part 3 – Runaway Climate Change