4th Class Science Our Environment Global Warming

       Global Warming

Global warming simply means increase in the average temperature of the earth's atmosphere. The sun's radiation falling on the earth is partly absorbed and a part of it is reflected back into the space. The part of the rays reflected back is trapped by our atmosphere. This trapped radiation further warms the earth, which is known as the greenhouse effect. This effect is however one of the major reason for life on this planet. The carbon dioxide present in the air is responsible for this greenhouse effect. Carbon dioxide is very essential for the life of the plants, but the excess amount of it is harmful. The amount of carbon dioxide is continuously on increase due to human activities and decreasing forest cover. The number of trees, which consume carbon dioxide is reducing, causing an increase in the carbon dioxide accumulation. Carbon dioxide traps heat and does not allow it to escape into the outer space.

   Global Warming  

 This results in an increase in the temperature of the earth's atmosphere. The process of gradual increase in the earth's temperature is called global warming. Global warming has becomes major concern worldwide. This is a serious issue and needs everyone to work for this alarming cause. Rise in even 0.5°C can cause glacier to melt and sea levels to rise. It has a wide range of other effects like, on the pattern of rainfall, agriculture, forest, plants and animals.

      The Gas responsible for greenhouse effect

(a) Carbon dioxide

(b) Methane

(c) Nitrous oxide

(d) Both (a) and (b)

(e) (a), (b) and (c)

Answer: (e)

     Global warming is known as:

(a) Average temperature of the earth's atmosphere is gradually increasing

(b) Average temperature of the sun's atmosphere is gradually increasing

(c) Portion of the globe which faces the sun

(d) Both A and B

(e) None of the above

Answer: (a)