A.    There are several causes of global warming, which have a negative effect on humans, plants and animals
B.    Global warming is a gradual increase in the earth’s temperature 
C.   The ozone layer protects the earth surface from the harmful ultraviolet rays emitted by the sun.It is caused by the release of greenhouse gases like carbon dioxide, methane, CFCs etc. into the atmosphere.
D.   With the excessive use of air conditioners and refrigerators, humans have been adding CFCs into the environment which affects the atmospheric ozone layer. E.    It is caused by the release of greenhouse gases like carbon dioxide, methane, CFCs etc. into the atmosphere.