•Over the last 200 years, industrialization has taken place. With new machines, sources of power and transportation, humans now have the tools to create liveable communities almost anywhere in the world.

•Now humans live in most parts of the Earth. We can alter the course of rivers, and even change the topography of the Earth’s surface with our great machines and technologies. Farms too can produce more food than before.

•New and better transportation allows food to move more quickly from place to place. All of these technological changes not only increase the food supply but also make it possible for the Earth to support billions of people.

•However, these changes also have harmful effects. We share the Earth’s environment with many other forms of living things. The large number of people living on Earth has affected the survival of many of these living things.

•Many kinds of plants and animals are now extinct. Even the atmosphere has changed. Changes in Earth’s temperature caused by global warming, ozone holes and acid rain are brought about as result of human activities.

•Burning of fuels like coal, oil and gas gives us energy to power the machinery factories, our homes and means if transportation. These burning produces carbon dioxide which keeps our atmosphere warm enough to support life. Without it, our planet would be frozen.

•Carbon dioxide in the Earth’s atmosphere acts like the glass of the greenhouse. It lets in sunlight and prevents the heat given off from escaping back into outer space.

•This is called the greenhouse effect.

•As humans burn more fuels to power more machines, the amount if carbon dioxide in our atmosphere continues to rise. However, too much carbon dioxide in our atmosphere will make the Earth too hot for living things to survive.

•This is known as global warming. If global warming continues, it will likely change the pattern if weather and climate all over the world.

•These changes will nit be the same everywhere, summers would become even hotter and the winters even colder. Larger and more powerful storms, greater periods of droughts in some regions, and increased rainfall in other could all be part of this new pattern.

•Another factor contributing to the increased amount if carbon dioxide in the atmosphere is the clear- cutting if rainforests. This is done to provide land for growing crops and timber for building. By cutting down trees, humans are taking away one of the nature’s way of cleaning the extra carbon dioxide from the air. However, human activities upset the balance of the gases in the atmosphere.

•All these increase the greenhouse effect and causes global warming.

•Global warming will change our climate drastically. It does not mean that everywhere on Earth is getting hotter. Some places would be warmer while others actually become colder. Some would even get drier while others wetter. The increased heat will change the global pattern of climate and weather, producing larger and more powerful storms, greater periods of droughts in some regions, and increased rainfall in others.

•Global warming melts the ice caps. The heat melts the ice at the poles, causing the sea level rise. A rise in the sea level will cause low- lying and coastal regions to be flooded.

•Our atmosphere is made up of many layers.

•Ozone is a molecule that is made up if three oxygen atoms. It forms a thin layer over the stratosphere. Ozone, at ground level, is dangerous to human health.

•In the stratosphere, this ozone layer absorbs most of the ultraviolet rays from the Sun. it protects the living things on the Earth from this harmful ray. It acts as the Earth’s sunscreen.

•In the 1970s the scientists discovered that the ozone layer was rapidly being destroyed. It was observed that at certain times of the year, the level of ozone in the ozone layer over the poles become so sparse that there is virtually a hole in that ozone layer.

•More harmful ultraviolet rays from the Sun will now be able to reach the Earth. Ultraviolet rays affect all life on Earth. There will interfere with the photosynthetic process, thereby damaging crops, plants and trees which form the basis of food chains that support life on Earth.

•When CFCs make their way to the upper atmosphere, they are broken down by ulrtraviolet rays to release chlorine. The chlorine released reacts with the ozone in the ozone layer to release oxygen and chlorine monoxide. Chlorine monoxide then combines with an oxygen atom to produce a molecule of oxygen and a free chlorine.

•The free chlorine atom then reacts with an ozone molecule, and the cycle repeats. More and more ozone from the atmosphere are destroyed, thereby causing the thinning of the ozone layer.

•Fortunately, many countries in the world are making laws to reduce the use of products made with CFCs, such as The Montreal Protocol in 1987 aimed to reduce the use of CFC by 50 % by 2000.

•Rain, even in polluted areas, is slightly acidic. This is because carbon dioxide in the air dissolves in rainwater to form a weak acid called carbonic acid.

•Besides releasing carbon dioxide, the burning of oil, coal and gas produces chemicals called nitrous oxide and sulfur dioxide into the atmosphere. These chemicals combine with the water vapor in the air and fall to the ground as acid rain.

EFFECTS OF ACID RAIN

•can damage surfaces of buildings & statues & kill forests

•The acidity of rain increases in industrial areas. Factories, power station using fossil fuels and exhaust fume from motor vehicles contribute to the higher concentration of chemicals in the air.

•Acid rain has disastrous effects. It kills fish, destroys trees, erodes the stone works of buildings and corrodes metals. Few plants can grow in acidic soil.

•Factories, power plants and oil refineries also increase the amount of greenhouse gases that are released.

•Burning fossil fuels such as petroleum, gas and coal releases carbon dioxide.

•Human beings create big cities to live and work. These cities have many concrete buildings and large surfaces of black roads, which absorb and retain heat from the Sun. This has also resulted in warming.

•When acid rain falls on trees, the trees lose their leaves and are unable to resist pests and diseases. Lakes and rivers may become too acidic for living things ti survive.

•We need to reduce the chemicals released into the air. Industrial power plants should install a device called “scrubber” in their chimneys to reduce the amount of sulfur released in the smoke. Motor vehicles should be fixed with catalytic converters into their exhaust pipes to reduce the amount of sulfur dioxide produced by the vehicles. We too should find ways to utilize fuels more cleanly and efficiently. This will greatly reduce the possibilities of acid rain developing in the atmosphere.