Explain the term 'global warming'. State two ways by which global warming can be reduced.

The rise in temperature of earth surface due to the heat trapped by greenhouse gases i.e., carbon dioxide, methane, nitrous oxide, ozone, chloro-fluoro-carbon compounds (CFCs) and water vapour present in the atmosphere is called global warming.

Two ways by which global warming can be reduced are :

1. Minimize use of automobiles : depending on the situation, one can use a bicycle or the public transport system and car pools.
2. Plant more trees to increase the green cover.