Last week, we had our long quiz for Ecology class. Among the questions asked in the test was:
“What’s the difference between greenhouse effect and ozone depletion?”
I had a smile running across my face when I got to this question, because I remembered that when we first discussed-briefly, about ozone depletion and the greenhouse effect; most of my classmates were talking to each other and saying that the two concepts are the same and that both are what’s causing the weird changes in the weather and climate today and that both were caused by man’s polluting activites.
Were they right? Not entirely.
They were right in saying that both are affecting our global weather and climate, however they were mistaken in thinking ang saying that both are the same and caused by mankind’s polluting activities. It’s not wrong to think that both are the same when throughout most of our lives, studying and encounter with environmental issues, the terms ‘ozone depletion’ and ‘greenhouse effect’ are always side by side or used interchangably, without giving much thought on their real meaning and in so doing both are not the same. They are different.
First off, greenhouse effect is the warming of the planet thanks to some of the solar heat that gets trapped by our atmosphere. You see, when solar heat reaches Earth, some of it gets reflected back into space by the atmosphere. Some passes through the atmosphere and gets scattered by clouds, gases and dust giving us heat and light. When it does reach the land another part of it is reflected back up but gets trapped again by the dust, gases and clouds in the atmosphere. Just like a big heater keeping our planet warm and cosy enough for life to thrive. The picture below illustrates in more detail how the greenhouse effect takes place. Just click on the thumbnail to view the full image.
So, is the greenhouse effect bad? If there’s too much of its effect, like what we’re experiencing now then it is bad. Extreme examples of this can be found in the planet Venus wherein the it suffocates from its own atmosphere of greenhouse gases like carbon monoxide, carbon dioxide and others. Of course when the opposite happens, our planet will be too cold life as we know it would find it very very hard to thrive and flourish.
Now on to ozone depletion. We all know that up in our atmosphere, is a layer of gases the provide us with an extra yet very important protection from the harmful radiation from the sun and space, it’s the ozone layer. Ozone in the earth’s stratosphere is created by ultraviolet light striking oxygen molecules containing two oxygen atoms (O2), splitting them into individual oxygen atoms (atomic oxygen); the atomic oxygen then combines with unbroken O2 to create ozone, O3.
This gas, though very limited in the atmosphere is what protects us from the harmful UV or ultraviolet rays coming from the sun, particularly UV-C which is the most harmful to us humans and we must thank the ozone layer for completely screening it out at 35kms up in our atmosphere.
Until of course, the ozone layer gets depleted, which is bad. There are two kinds of ozone depletion, one is naturally occurring and the other is man-made. The natural depletion of the ozone takes place seasonally in both poles of the Earth; North and South. The so-called “ozone holes” we’ve seen pictures of in television shows, magazines and the web. The bigger problem is the depletion of the ozone layer that occurs below the Artic and Antartic circles which is right above were humans live. Ozone or O3 is very unstable, like a fragile puzzle that gets easily split apart thanks to CFCs or chlorofluorocarbon compounds which we mass produced decades before we found out about the ozone layer was up there and that these compounds were destroying it. That’s why these compounds formerly used in refrigerators, airconditioners, paints, aerosol sprays etc were banned from being used or produced worldwide.
So there you have it, greenhouse effect = good as long as there’s not too much of it now that’s global warming and ozone depletion is bad, very bad. So let us do our share, protect the ozone, protect our selves, protect our planet.