- Books Name
- Class-8 Science Book
- PathSet Publications
- CBSE Class 8
The Greenhouse Effect
- As the sun rays enter the earth's atmosphere, some of the radiation gets reflected back into space while some of it is trapped inside the earth's atmosphere.
- This is possible because of certain greenhouse gases in the earth's atmosphere which can trap the heat of the sun. For example, carbon dioxide, methane, nitrous oxide and water vapour can trap the sun’s radiation inside the earth. This phenomenon is called the greenhouse effect.
- Due to this greenhouse effect, the earth has a stable temperature that can support the existence of life on it. The greenhouse effect provides the required warmth to the earth.
- However, due to excess carbon dioxide in the atmosphere, the greenhouse effect is becoming serious trouble for the earth.
- The excess of greenhouse gases leads to the absorption of more heat inside the Earth which further leads to a gradual rise in the temperature of the Earth. This phenomenon of increased temperature of the earth is called global warming.
Sources of Carbon Dioxide on Earth:
- Human activities such as the burning of fossil fuels and industrial activities etc are causing a release of carbon dioxide into the atmosphere.
- Cutting of Forests imbalances the carbon dioxide and oxygen amounts in the air as plants take up the carbon dioxide from the environment and in return release oxygen. Therefore deforestation leads to the increased presence of carbon dioxide in the atmosphere.
Effects of global warming
- Global warming leads to an increased temperature of the Earth which causes the melting of the glaciers and therefore increased sea levels. Hence, it results in flooding the areas around the sea.
- It also leads to extreme weather conditions in different places of the earth.
- Increased rainfall in different places has occurred due to the higher temperatures of the earth.
- Extinction of species or loss of habitats is occurring due to global warming as the animals are not able to adapt to changing climatic conditions of the earth.
What is the Ozone Layer?
- The earth’s atmosphere is covered with a layer of ozone gas all around.
- This ozone gas prevents the dangerous ultraviolet rays of the sun from reaching the surface of the earth.
- The ultraviolet rays of the sun if reach the earth’s surface can cause severe problems.
- They can affect the plants, cause cancer in human beings, skin and eye diseases and can harm all other biotic and abiotic components of the earth.
- Hence, the ozone layer has a significant role in the environment.
What is ozone layer depletion?
The ozone layer can be termed as deterioration of the ozone layer due to the presence of harmful substances in the environment. The main cause for the depletion of the ozone layer is CFCs or Chlorofluorocarbons. They react with the ozone gas and form molecular oxygen.
Prevention of Air Pollution
- Switching to cleaner fuels like CNG and LPG can lead to decreased air pollution.
- Generating awareness among people about air pollution and its harmful effects will encourage them to participate in preventing it.
- Increasing the usage of solar energy, wind energy and hydropower.
- Planting more and more trees around the cities in rural areas. India celebrates ‘Van Mahotsav’ in July every year when people come together and plant trees on a large scale.
- Instead of burning dry leaves and other organic materials, they should be dumped into compost.
- Using gas stoves instead of burning coal or wood to cook food.
- Sharing vehicles or using public transport to reduce the number of vehicles on the road and hence the air pollution.
- Using eco-friendly paints and cleaning products for households and other buildings.