Even the Punishment of the World is Mercy in Disguise
In the verses cited above, after having mentioned various punishments which could seize disbelievers within this world, it was said in the end: فَإِنَّ رَبَّكُمْ لَرَءُوفٌ رَّحِيمٌ (So, indeed your Lord is Very Kind Very Merciful).
First of all, by using the word: رَبّ (Rabb: Lord) here, the hint given is that all these punishments which overtake human beings in this world are there to warn them as part of the dictates of Divine mercy. After that, by introducing the word: رَءُوفٌ(Ra uf: Kind) headed by the intensifying particle lam) that is, the lam of ta'kid), and thus by placing stress on the fact that Allah Ta’ ala was Very Kind and Very Merciful, the hint given was that warnings sent during the life of the world were, in reality, called for by His intrinsic Kindness and Mercy so that heedless men and women would learn from the warning and correct their deeds (before comes 'the last spasm of mass extinction' they themselves are talking about at the closing of the twentieth century, but are still not ready to learn, believe and correct).