With the growing concern over the climate and our environment, understanding what green house gases are becomes more important than ever. There is a problem with this, though. There are many definitions, some technical and others in layman’s terms. Some are specific and others aren’t. This is at the crux of the entire heated debate about whether man is causing global warming or not, and if he is, what can be done about it.
For the best definition, it is a good idea to understand a little about the greenhouse affect. At its most basic, when heat from the sun passes through the glass or plastic of a greenhouse, it loses a little energy. It no longer has the energy to escape back through the glass or plastic, so it heats the interior of the greenhouse. This is the greenhouse affect.
Using this knowledge, we can then say that a greenhouse gas is any substance in a gaseous state, present in our atmosphere, which causes the same thing. The part about “in a gaseous state” does need explanation, for further understanding.
There are four states of matter: solid, liquid, gaseous, and plasma. We will disregard the fourth state since this is not important to this discussion.
The first three can be shown in the example of water. Water exists as solid – ice, liquid – liquid water, and as a gas – steam or clouds.
The same is true of most substances. So any atmospheric element or compound that traps heat while in the gaseous state is a greenhouse gas.
As a side note and a bit of trivia: Glass is actually a liquid, technically. Given enough time, a vertical pane of glass will become thicker at the bottom and thinner at the top, as the glass slowly “flows” down.
All of this means that many substances not thought of as greenhouse gases really are. For example, while clouds do reflect some of the sun’s rays back into space, they allow the lower wavebands; those that produce heat, through without letting it escape again.
This makes water vapor, or gaseous water, a greenhouse gas. Many people won’t agree with that, but it is true. Further, since there is more water vapor in the atmosphere than any other gaseous compound, water is the most abundant greenhouse gas of all.
Other common greenhouse gases: Carbon dioxide, methane, butane, propane, sulfur dioxide, and hydrogen sulfide. Note that all of these are toxic to human life, if they are in concentration.
Luckily, none of them are in concentration, normally. Carbon dioxide levels, for instance, have fluctuated greatly, based on all the means we have to measure them. At the same time, they are all naturally occurring.
Greenhouse gases also have their worth. Without them, the earth would be a frozen ball. There are enough greenhouse gases to trap heat to make this world habitable.
So why is there so much concern about greenhouse gases? The answer is that again, in concentration, they can cause problems. Too much of a good thing is seldom good. If there were a sudden increase in greenhouse gases, global temperatures would soar.
There isn’t such an increase, and it isn’t likely there will be since there is a finite amount of both carbon and sulfur, the main constituents of greenhouse gases other than water vapor. Both elements are strongly locked in to both water and rock.
All living things are also carbon based. This is a double-edged sword, though. A major forest fire releases thousands of tons of carbon into the atmosphere, and a volcanic eruption releases both carbon and sulfur. In fact, fires and eruptions produce more of both elements into the air than any other source, by far. In fact, in a closed system like ours, man doesn’t have the ability to release as much of either, in the quantities that nature does.
Understanding what greenhouse gases really are, is the first step to becoming enlightened about the controversies. Without this knowledge, nobody can even make an informed guess. That doesn’t stop the uninformed guesses, though.