If decomposers are removed completely from the Earth, then dead bodies of plants and animals or other dead organic matter will remain undecomposed. The complex nutrients will not be made available back to atmosphere. After some time, the dead bodies of organisms will acquire the whole space on the Earth. Thus, existence of life will be impossible on the Earth.

Our atmosphere acts as a blanket because:
(i) It keeps the average temperature of the earth fairly constant during the day.
(ii) The atmosphere prevents the sudden increase in temperature during the daylight hours.
(iii) During the night, it slows down the escape of heat into outer space.

(i) Global warming 
(ii) Environmental pollution
(iii) Depletion of ozone layer.

Harmful effects of air pollution
(i) Respiratory problems
(ii) Acid rain or Global warming.

The concentration of carbon dioxide in the atmosphere is increasing due to the current global trend of deforestation and increasing combustion of fossil fuels. A part of the sunlight incident on the earth reflected back in the form of infrared radiations. This infrared radiation are absorbed by the carbon dioxide molecules. hence, the envelope of CO₂  of the atmospheric air would be able to trap larger proportion of the infrared radiations if the concentration of CO₂ is increased, thereby heating the atmosphere.
This heating of the absorption of infrared earth's temperature and may cause melting of glacier and thereby flooding the coastal plains.
Greenhouse gases:
(i) CO ₂ ,  
(ii) Methane (CH₄ ) and
(iii) Nitrogen oxide.

The concentration of carbon dioxide in the atmosphere is increasing due to the current global trend of deforestation and increasing combustion of fossil fuels. A part of the sunlight incident on the earth reflected back in the form of infrared radiations. This infrared radiation are absorbed by the carbon dioxide molecules. hence, the envelope of CO₂  of the atmospheric air would be able to trap larger proportion of the infrared radiations if the concentration of CO₂ is increased, thereby heating the atmosphere.
This heating of the absorption of infrared earth's temperature and may cause melting of glacier and thereby flooding the coastal plains.
Greenhouse gases:
(i) CO₂ , 
(ii) Methane (CH₄ ) and
(iii) Nitrogen oxide.

The term water pollution covers the following effects:
(i) The addition of undesirable substances to water bodies: For example, addition of industrial wastes containing poisonous salts like mercury salts, pesticides, insecticides, etc. Addition of disease causing organisms, like cholera causing bacteria through sewage. 
(ii) The removal of desirable substances from water bodies: For example, depletion of dissolved oxygen and nutrients. This adversely affects aquatic animals and plants.
(iii) A change in temperature of water in water bodies: The aquatic animals are adapted to live under certain range of temperature. A sudden change of temperature may affect breeding of aquatic animals, their eggs and larvae etc. For example, pouring of water at very high temperature from nuclear reactors sometimes may cause death of fishes and aquatic animals.

There are two types of sources of water pollution. These are:
(i) The sources which are located to close to water source and discharge pollutants directly into the particular water source. These may be factories, power plants, underground coal mines and oil wells situated near to water sources. It is possible to treat the pollutants before their release into the water body.
(ii) Some sources are scattered and do not have specific situation for discharging pollutants into a particular water body. These are run-off water from agricultural fields, gardens, lawns, roads, logging sites, construction sites etc. It is very difficult to monitor, regulate and treat non-point sources.

The messages that the children sent out to the public on EARTH DAYwere:

• How would you feel if somebody drew a nail into you?
• Even trees feel the pain
• Do not nail advertisements on trees
• Do not nail advertisements on trees
• Do not throw plastic bags in parks,gardens,etc They spoil the advertisement Always collect them and throw them in dustbine
• Join the stufdents of Delhi in saving the greens.
  (b) similar activities could be carried out in any town and city and one needn't wait for the Earth day or environment day top act that it was only through actions that we could bring about a change in peoples attitudes
  (c) Social responsibility
  (2) Keep the environment clean.

It is very necessary to replenish forests for the following reasons:
(i) Rainfall: Trees give out enormous amount of water during transpiration. This water vapour helps in the formation of rain clouds. If trees are destroyed and not replenished the rainfall in the area will reduce. This may lead to less number of trees to grow.
(ii) Soil erosion: If trees are cut at a large rate the soil becomes barren. The top soil which is rich in organic matter will be washed away by water or carried away by wind. Thus reduction in rainfall and soil erosion may lead to the formation of desert.
(iii) Carbon dioxide-oxygen balance: Forests have very large number of trees. They give out \({ O }_{ 2 }\) and take in \({ CO }_{ 2 }\) in day time by the process of photosynthesis. Thus they help in maintaining carbon dioxide-oxygen balance in the atmosphere.

During the water cycle, water is found in solid-state (snow, ice, etc.), liquid state (groundwater, river water, etc.), and gaseous state (water vapours).