GSEB Class 8 Social Science Notes Chapter 7 Environmental Changes

   

This GSEB Class 8 Social Science Notes Chapter 7 Environmental Changes covers all the important topics and concepts as mentioned in the chapter.

Environmental Changes Class 8 GSEB Notes

→ The air that envelops earth from all sides is called Atmosphere.

→ The atmosphere is getting polluted due to human activities like industries, factories, power stations, auto vehicles, etc.

→ Changes occurring in temperature, wind direction, rainfall, etc. due to global warming are known as ‘Environmental Changes’.

→ The condition of temperature, humidity and rainfall in a region at a particular point of time is called ‘Weather’.

→ The average condition of rain, temperature, and moisture for over 35 years in a region is called ‘Climate’.

→ Countries with cold climate receive less heat from the sun. This hampers growth of plants and vegetables. Thus, arrangements are made to conserve heat by having a roof of glass or cloth to allow sunrays to reach inside and sustain heat. This is known as ‘Greenhouse Effect’ and this type of farming is called ‘Greenhouse Farming’.

GSEB Class 8 Social Science Notes Chapter 7 Environmental Changes

→ Global warming means unequal and continual rise in average temperature in Earth’s climate due to greenhouse effect. Certain gases entrap infrared rays (UV radiation) so that the temperature of Earth increases. The planet becomes warmer. This effect is known as ‘Global Warming’.

→ Carbon dioxide, methane, nitrous oxide, chlorofluorocarbon (CFC), halo carbon, etc. are known as greenhouse gases. These gases retain heat.

→ Increase in their proportion leads to problems of global warming and climatic changes.

→ Temperature of Earth has increased by 0.6 °C in the last 100 years.

→ An average person releases about 4.5 metric tonnes of carbon dioxide (CO2).

→ 100 years ago the amount of C02 was 275 PPM (parts per million), today it is 350 PPM.

→ In 1750, the proportion of methane was 315 PPM, which increased to 1764 PPM in 2005.

→ The proportion of nitrous oxide has increased from 270 PPM to 319 PPM.

→ Due to increased use of foam, plastic, fridge, A.C. circuit, aerosol spray (Aerosol are minute particles ranging from 1 to 10 microns) etc. the level of chlorofluorocarbon (CFC) has increased in the atmosphere.

→ Effects of Global warming:

  • Changes in growth and development of vegetation.
  • Frequency of natural calamities like drought, excessive rainfall and cyclones has increased since last 10 years.
  •  Melting of glaciers has increased ocean water level causing extensive erosion along the coastline. Also areas near the coast of Maldives, Bangladesh, Australia, etc. have been submerged.
  • Frequency of diseases like cholera, dengue, malaria, swine flu, etc. has increased.

→ Solar energy, wind energy, tidal energy, biomass, etc. are non-conventional sources of energy.

→ Measures to Prevent Global Warming:

  • Reduce the use of sources which release CO2.
  • Afforestation and conservation of forests.
  • Growing plants and trees around your house to reduce Carbon dioxide.
  • Avoid using plastic.
  • Optimum and judicious use of manure, pesticides, household appliances, natural resources, petroleum products, electricity, means of transport and water.
  • Control population, etc.
  • Practice rainwater harvesting.

GSEB Class 8 Social Science Notes Chapter 7 Environmental Changes

→ Conferences were held first at Stockholm, the \ capital of Sweden in 1972, and then at Rio de Janeiro of Brazil to think of ways to protect the environment. In a meeting held at Copenhagen, the capital of Denmark, in 2009 it was observed that developed nations like USA should adopt the ‘Carbon Cut’ policy seriously as every US citizen produces 20.6 metric tonnes of greenhouse gases, and the developing countries like India should be given an aid to the tune of about 100 billion dollars.

→ An average person releases 4.5 metric tonnes; an average Indian releases 1.2 metric tonnes and a citizen of USA releases 20.6 metric tonnes of carbon (greenhouse gases).

→ 16th September is observed as ‘Ozone Day’ all over the world.

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