The world before the Flood was starkly different from the world today (as even science will attest), and the destruction of the world under a layer of boiling water was an event without parallel in nature or history.
Rabbi Avigdor Miller, zt”l, remarks on a fascinating aspect of the destruction that is often overlooked: the magnitude of the recovery. The renewal of human, animal and plant species from near annihilation was as much a miracle as the destruction itself.
“From all the living, from all flesh, two of each you shall bring into the ark” (6:19). At the beginning, all animals were equally distributed over the earth, for the climate everywhere was mild and uniform. ln the arctic regions, we today find thousands of frozen carcasses of mammoth elephants preserved in the permafrost, which indicates a previously temperate climate that suddenly changed and quick-froze the bodies so that even their eyeballs are perfectly preserved.
In their stomachs, and even in their mouths, are buttercups and other plants of which nothing today can grow in the severe cold of those regions. It is evident from fossils everywhere that previously there had existed a more even distribution of plants and animals. Therefore the animals that entered the ark did not need to travel great distances, because all of them were available in the vicinity.
It is understandable that the Flood uprooted trees and shrubs, and therefore everywhere there were floating masses of land vegetation tangled with seaweed and loaded with muddy debris, on which insects of all kinds were enabled to subsist for the duration of the Flood. These floating masses were not substantial enough to support animals, and certainly could not keep them alive for the twelve months of the Flood.
The Flood marked an end to the old world and a completely new beginning for the new world. Now all mankind would trace its ancestry to Noach alone, instead of to the many contemporaries who had lived in his generation. But an even more novel world began for all the beasts and fowl and other living creatures.
At Creation, countless cattle and deer and lions came into being; and from them a vast progeny had developed. Now, only one pair of a kind remained from which all of that kind were to develop. Thus the Flood necessitated a new Creation, accompanied by astonishing phenomena that were never repeated subsequently.
A single pair of each species, caged in the ark and deprived of its natural environment for 12 months, has little chance of survival. Even after being released from the ark, one lone pair could have little chance for survival. The fact that all the species survived the ark, and afterward succeeded in populating the earth, was an enormous marvel.
The migration of living things to the ark, and their dispersal and survival after the Flood, were wondrous events almost as marvelous as the events of Creation. This stupendous series of events could have been avoided, with G-d destroying the sinners and preserving the species in ways that would seem natural to us.
But there was a reason for this grand spectacle of the rebirth of the world in such astonishing manner: to proclaim the principle that the world was recreated anew because of one virtuous man. Mankind learned that the righteous individual is so important in Hashem’s sight that for his merit the entire Creation is repeated with demonstrations that were never afterward witnessed.
Thus, when we today see an ox or a bird, we know it is derived from an inhabitant of the ark; and all men today are descendants of those who were preserved in the ark that Noach built. Thereby all the living today testify to the fundamental principle that the man who “walked with G-d” (6:9) was the cause of the rebirth of the world. (From The Beginning)