It's The End of the World as We Know It

The apocalypse seems to be almost inevitable.  Whether it's a decade from now, a century from now or billions of years from now, the end of the world is a sure thing.  The real question is- how will the world end?  In The Road, there are multiple hints to the reader that the world ended in perhaps an outbreak of disease or a series of natural disasters.  In other words, it appears to have been some form of nature that destroyed both the plant and animal populations. 
Some evidence of disease occurs on page five of the book where it mentions the young boy taking his mask off in his sleep.  This gives the reader an image of a surgical mask.  This mask could possibly used to keep the boy safe from bacteria if the end of the world occurred from disease.  However, this mask could also be used for keeping ash out of the boys mouth.  If the world had ended from a series of natural disasters, the boy may wear the mask to keep out ash from volcanic eruptions.
Also, there is evidence of natural disasters a few pages later on page 28.  While the boy and father are in the foothills of the eastern mountains, the ground begins to shake.  The boy becomes terrified, and the father explains it is an earthquake.  The boy's reaction to the earthquake shows that he may have witnessed even worse earthquakes before this one.  Also, the apocalypse may have been larger disasters that are still fading away, leaving behind tiny trembles.
A short while after this on page 32, the father has a dream about his wife.  In his dream he is caring for his wife while she is sick.  However, in reality he did quite the opposite.  He left her to die alone, but more than likely he left her because he had to.  The boy is the father's reason for living, so he probably left his wife in order to keep the boy safe.  This tells the reader that the boy probably had a high risk of becoming ill and dying as well if it forced the man to leave his wife to die alone, and the end of the world was caused by a deadly disease.
The novel shows a plethora of evidence showing that the world ended in Cormac McCarthy's novel, The Road, by a disease or a series of natural disasters.