While explaining environmental issues, teacher

While explaining environmental issues, teacher makes a remark that ‘Global warming is the most serious threat to civilisation now’.
Kalpana gets curious about the various aspects of global warming and asks some questions to her teacher.
(i) What is g;obal warming ?
(ii) What are various causes of global warming?
(iii) What values are shown by Kalpana?

(i) The gradual continuous increase in average temperature of surface of the earth, is called global warming.
(ii) Various causes of global warming are:
(a) High level of greenhouse gases in the atmosphere.
(b) Rise in atmospheric temperature
(iii) Kalpana is inquisitive, attentive and environment friendly.