Tree planting lessens ozone layer damage

Opinion Saul Gwakuba Ndlovu
The world is looking into a global phenomenon referred to as “climate change”, a development said to be caused by the warming up of the earth’s surface and that of its relevant atmospheric environment. This is a very interesting scientific issue with extremely important practical consequences to the whole world as we know it today.

Climate is the prevailing weather conditions of a region or country, continent or the world at large observed and analysed daily over a period of say, 50 years. While two major factors, altitude and latitude, determine climates of various regions, other factors such as large bodies of water and their currents, the concerned region’s proximity to those bodies of water, prevailing winds and the physiographical features of an area, have direct effects on their climate.

We have been told that some industrial omissions and gases are depleting the ozone layer, resulting in the sun’s rays reaching the earth as raw as they would have left the fiery heavenly body without having been first filtered of their ultra-violent rays. We know that for human beings excessive exposure to the sun’s hot rays can result in some type of dermatological conditions such as one or the other kind of skin cancer. We are referring to rays that would have passed through the normal ozone layer gas.

We are not aware what effect the depletion of the ozone layer has or is likely to have on various types of animals, that is aquatic as well as terrestrial. But some scientists say it could be lethal. It would appear that the negative effects of uncontrolled industrial gas emission will either destroy or change the world’s current plant and animal life. This is, of course, looking at the matter on a long term basis.

The ozone layer is situated about 65km above the surface of the earth, and the ozone itself is, in fact, oxygen but with three instead of two atoms in each molecule. It is that gas at that altitude that absorbs the sun’s ultra-violet rays, making them safe for the earth’s flora and fauna, including what zoologists and botanists call benthos, a reference to plants and animals found at the bottom of seas, lakes, huge dams and swamps.

It would be most helpful to know how the depletion or alteration of the ozone layer will affect the water in the rivers, dams, lakes, seas and oceans. We know that the sun’s rays travel some 149 million kilometres to reach the earth, and that they pass through first, the exosphere which is some 256km above the earth’s surface highest point (Mount Everest), then the ionosphere, then the chemosphere that is some 144km above Mount Everest, and then through the stratosphere, some 16km up there in the sky, and then through the troposphere, some 10- 13km above Mount Everest.

The end of the troposphere, just below the stratosphere is called the tropopause. Sun light rays hit the earth’s surface more or less vertically at the equator, and produce greater heat there than further south or north of the equator where they are oblique and thus radiate less heat. This latitudinal factor affects all equatorial regions where we find very high temperatures. Further away from the equator at the north or south poles, for instance, temperatures hit a marrow — freezing low of -68c at Oimyakon in Siberia, and -87c at Vostock in the Antarctica in the South Pole.

Latitudinal factors cannot be adversely affected by industrial emission, however. It is the ozone layer, situated some 65km above the earth, that is of much concern to us, because it is vulnerable to industrial development whose gaseous wastes have disastrous effects on the atmospheric environment.

The atmosphere comprises 78 percent nitrogen, 21 percent oxygen, plus smaller measures of carbon dioxide, argon, water vapour, dust, bacteria, pollen and suspended particles of various types of dirt. People can change the amount of atmospheric carbon dioxide by planting trees on a large scale as tree leaves during the day utilise quantities of carbon dioxide and emit oxygen.

Zimbabwe can, without much financial capital, establish tree plantations in each of its 10 administrative provinces. A scientific analysis of the soil of each province can indicate the tree species suitable for each area. Tree plantations such as those found in Swaziland and Australia can reduce the country’s atmosphere’s dust content, and increase its oxygen level. That could contribute to the maintenance of the normal ozone layer.

The building of huge dams in various parts of the country, especially in the drought-prone regions, can increase the country’s water vapour levels through evaporation, which could lead to condensation, with heavier precipitation as a result. Tree plantations located against hopefully moisture — laden winds would deflect them upwards to an altitude where condensation occurs, thus also creating favourable precipitation conditions. Growth of vegetation and thus an increase of the oxygen level would be greatly assured.

Environmentally destructive actions or practices such as veld fires and the wanton destructions of wooded areas, especially well established wind- deflecting forests have negative impact on the climate, as they cause a globally warming up effect generally referred to as the “greenhouse effect.”

This means, in fact, that it is good for plants, hence the expression. It is, however, certainly not good for the animal kingdom. This is because the process of photosynthesis (that is, the synthetisation of carbohydrates from carbon dioxide and water by, especially, green plants by the use of sunlight energy) is greatly enhanced by “greenhouse” gases.

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