I believe that our earth is going through a transition that it has always done since it was created about 6.5 billion years ago(according to scientist). There is a cycle that the planet goes through about every 50,000 years, or so, and we happen to be around right in the middle of it all. The native peoples all talk of a cleansing that the world goes through when the Great Father is unsatisfied with how we are all behaving in the world. Many civilizations and these include Asian, Indian, Aztec, and such people who predict the future, claim that it is now time for the last days and that we will soon undergo those events included in the scriptures of the Bible. We have no real way of determining this, however, we should all be prepared in living only one day at a time and not to worry about tomorrow. As you said "Natural Calamities" and this is just it, they are mostly natural, although some are very likely man made.