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Topic 4

ECOLOGY

The problems facing the environment are vast and diverse. Destruction of the world’s rainforests, global warming, and the depletion of the ozone layer are just some of the problems that will reach critical proportions in the coming decades. Their rates will be directly affected by the size of the human population.

The more civilization is developing, the greater the ecological problems are becoming. Factories, power stations and motor vehicles pump large quantities of carbon dioxide and other waste gases into the air. This is a major cause of the greenhouse effect. Smog, usually found in urban areas, can cause brain damage in children and other serious health problems.

Some poisonous gases dissolve in water in the atmosphere and then fall to the earth as acid rain. Acid rain has made numerous lakes so acidic that they no longer support fish populations. Acid rain is also thought to be responsible for the decline of many forest ecosystems worldwide. Rivers and lakes are also polluted by chemical fertilizers and pesticides used by farmers.

The greenhouse effect has lead to global warming. Normally, heat from the sun warms the earth and then escapes back into space. But CO₂, SO₂ and other gases trap the sun’s heat, slowly making the earth warmer. Scientists say the temperature of the earth could rise by 3^oC over the next 50 years. This may cause drought in some parts of the world, and floods in others, as ice at the North and South Poles begins to melt and sea levels rise.

The ozone layer is a thin band in the stratosphere that serves to shield the earth from the sun’s harmful ultraviolet rays. The depletion of the ozone layer is caused by substances called CFCs used in refrigerators, aerosol cans and in the manufacture of some plastic products. Increased ultraviolet radiation will lead to a growing number of skin cancers and also reduce the ability of people’s immune systems to respond to infection.

Most of the energy we use today comes from coal, oil and gas. But these will not last forever, and burning them is slowly harming the atmosphere. Nuclear energy as an alternative is opposed by many because of the massive devastation an accident can cause. The accident at the Chernobyl nuclear power plant in 1986 scattered radioactive contamination over a large part of Europe. 70 per cent of the radiation descended in Belarus. Approximately 135 000 people were evacuated, and human health has been dramatically affected. The World Health Organization released a report in late 1995 attributing the “explosive increase” in childhood anemia, thyroid cancer in Belarus, Ukraine, and Russia directly to the accident.