Genesis 8:23 'And every living substance was destroyed which was upon the face of the ground, both man, and cattle, and the creeping things, and the fowl of the heaven; and they were destroyed from the earth: and Noah only remained alive, and they that were with him in the ark.'
Worst natural disaster ever? That's an easy one. The Great Deluge of Noah. All breathing creatures on the face of the earth were destroyed except for a single male/female pair of every species plus Noah, his wife, their three sons and their three wives. How many died? All except for the eight on the ark.
Not entirely true. While indeed Noah was commanded by God to bring into the ark by twos, he was also admonished:
"Of every clean beast though shalt take to thee by the sevens, the male and his female: and of the beasts that are not clean by two, the male and his female.
Of fowls also of the air by sevens, the male and his female; to keep seed alive upon the face of all the earth." Gen 7:2,3 (emphasis in italics mine).
In Genesis 6 what is stressed is the pairing of animals that were brought into the ark. However, in Gen 7 it is clear that a number of pairs of certain species was preserved.
What is important to observe here is:
1. God's care for man, for his comfort and benefit. We do not find that Noah was solicitous of himself about this matter; but God consults our happiness more than we do ourselves. Though God saw that the old world was very provoking, and foresaw that the new one would be little better, yet he would preserve the brute creatures for man's use. Doth God take care for oxen? (1 Cor 9:9). Or was it not rather for man's sake that this care was taken?
2. Even the unclean beasts, which were least valuable and profitable, were preserved alive in the ark; for God's tender mercies are over all his works, and not over those only that are of most eminence and use.
3. Yet more of the clean were preserved than of the unclean.
(1.) Because the clean were most for the service of man; and therefore, in favour to him, more of them were preserved and are still propagated. Thanks be to God, there are not herds of lions as there are of oxen, nor flocks of tigers as there are of sheep.
(2.) Because the clean were for sacrifice to God; and therefore, in honour to him, more of them were preserved, three couple for breed, and the odd seventh for sacrifice, (Ge 8:20). God gives us six for one in earthly things, as in the distribution of the days of the week, that in spiritual things we should be all for Him. What is devoted to God's honour, and used in his service, is particularly blessed and increased.
There never was a global flood. The Noah story interpreted that way is just not true.