P: The main cause of global warming is the human being's careless activities.
Q: There are many causes of the global warming which affects human lives and health in many aspects.
R: Fossil fuels burning for many reasons are highly responsible to increase global warming.
S: Ever increasing human population is demanding more resources to live easy and healthy life such as land to live and for crop cultivation, technological growth for comfort and to deal with increasing temperature of atmosphere, etc.