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.

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.

Cause of Acid Rain: Dissolution of different oxides of nitrogen (e.g., \({ NO }_{ 2 }\)) and sulphur (e.g., \({ SO }_{ 2 }\)) in rain water in the atmosphere causes Acid Rain. These oxides of nitrogen and sulphur are produced due to combustion of fossil fuels.
Consequences of Acid Rain
(i) Acid rain cause increase in acidity of the fertile soil and also damages chlorophyll of leaves of crops and other plants. Thus, indirectly reduces crop yield.
(ii) Acid rain corrodes metal, stones and marble, painted surfaces etc. Thus, harms our heritage monuments, statues and buildings.
(iii) By acidifying water, acid rain also harms aquatic life.

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.

The topmost layer of soil that is loose, fertile and helps in the growth of vegetation gets carried away by wind and rain water is called soil erosion.