1) Not enough room on the ark.
The bible gives the dimensions of the ark in cubits, but in modern measurements it was 515×86 ft, and 52 feet high, or about 2.3 million cubic feet. For comparison the empire state building (which probably couldn’t fit all of the animal species in the world either) is about 37 million cubic feet. Creationist websites say the average volume of animals on earth is about the size of a cat, anti-creationist sites tend to say about the size of a sheep. Lets go with the cat just to be extra-fair. The first website I could find that actually gave the volume of a household cat estimated it at 648 cubic inches, so lets go with that. Now assuming the ark was completely hollow, had no support beams, levels, partitions of any kind, and that the animals were all stuffed in like sardines with no breathing room, food, fresh water etc whatsoever, the ark would need to be 93,977,820 cubic feet, or about 30 times larger to accommodate all known species of life. You may argue that some species could survive a flood and don’t need to be counted, which is not true for reasons discussed below, but even if you leave out all the fishies, ducks and other underwater or floating species, the ark is still woefully inadequate, so I don’t need them to debunk the story.
According to genesis the flood lasted about a year, from the first flood waters to noah first finding land again, which means they would have had to have food (and fresh water, and a way to keep it from going stagnant for a year in the bronze age) for 1.7 million species, all with specialized diets. It’s not like they could all get by on beef jerky or something, noah would have to get a year’s supply of bamboo from china for the panda bears, a year’s supply of insects for countless animals etc. This is especially difficult since half of the animals on the ark eat… the other half of the animals on the ark, necessitating that he would have to get exponentially more animals than the crushing amount already tallied.
3) Gathering the animals.
On flat terrain the average walking speed is 3 mph. Assuming the earth were flat and no oceans had to be crossed and assuming that the average trip distance to get all the animals on the earth were about half way around half of the earth and back, that’s 26,000 miles per trip two ways. Even with 20 people helping him (which he didn’t have), carrying 2-7 of 10 species per trip average and the helpers had no need of food or sleep (and neither did the animals) and that they could haul a massive herd of diverse species at the same rate that we can walk unhindered, it would take them 5,431 years just to collect the few thousand species of mammals! Let alone the million plus total species. But creationists often argue that god made the animals magically walk to noah from everywhere in the world spontaneously. Assuming this impossible thing is true it would mean polar bears, penguins and amphibians walking through the desert for tens of thousands of miles, when a few days in those environments would be as lethal to them as a few days under water would be lethal to you. They would also have to make the trek without food, since they would leave behind all the species they subsist on. Though creationists would probably claim that hordes of other animals came along and offered themselves up as snacks along the way to make the story more plausible.
4) Loading the animals.
Noah and his wife, and his kids and their wives make up 8 people. The bible says they loaded all the animals on the ark in one day. Now without getting into the logistics of converting animals into high-pressure liquid in order to fit them into the ark, as noah would surely have needed to do, as with all of the items on this list lets ignore all of the other impossibilities to evaluate the current impossibility. Lets assume all the animals came to noah on their own accord, that they fit on the ark, that they wouldn’t immediately start eating each other etc. Each member of noah’s family would have had to load 212,500 species through the same door, in the same day. Talk about labor intensive. Imagine the anarchy. The imaginary, imaginary anarchy.
As anyone who has a pet or a brain knows, animals have one universal downside – they insist on eating food and drinking water (the ingrates!). Lots and lots of it. The average human must consume about 2 liters a day of water to survive. Noah and his family would have required a at least 12,875 pounds (6.5 tons) of fresh drinking water, and a way to preserve it. You can imagine how much the animals would require. In truth even if water didn’t stagnate, they would need a fleet of arks to supply the fleet of arks they would need to fit all the animals onto.
6) Tending to the animals.
Imagine you ran a zoo single-handedly. How many animals could you feed, water and clean up after (assuming unlimited resources)? Think about it, would it be 10? 20? Maybe 50 if none of them were dangerous or difficult or too large (thus more to clean up after), right? Again assuming all of the above and below impossibilities were not a problem, they would still need to feed, water and clean up after the animals on the ark for a year. Each member of noah’s family would need to feed, water, and clean up after 686 mammal species each, 1,135 reptile species each, etc, etc. And a total of over 200,000 species each, every day. And bear in mind genesis said that there were 2 of some animals and 7 of others depending on whether they were “clean” or “unclean”, so that’s anywhere between 2,270 and 7,945 reptiles per person, per day. Without pay or pension!
7) Barometric pressure.
Barometric pressure is the weight of the atmosphere pressing down on us. The more stuff in the sky the more pressure, and enough pressure will kill you. When it rains or is about to there is a large volume of water in the air, increasing that pressure, which can aggravate some medical conditions. Some have done the math of what the barometric pressure increase would be and supposedly it would be lethal to life. I’m bad at math so I’m glossing over this one.
8) Seedless plants and insects.
In addition to the vast numbers of animals which could not survive the flood, countless species of plants and insects also cannot survive under water. Creationists often at this point in the discussion cite the few insects that can and claim plant seeds could survive. Assuming they wouldn’t rot to nothing in a year (which they would), that still leaves out seedless plants and non-aquatic insects. It’s also worth mentioning that many modern living trees actually pre-date the supposed flood by several thousand years.
Not the threat of it, but the preservation of it. I will let this excerpt from mark twain’s satirical account of the flood in Letters From The Earth (well worth the read) explain:
“On the third day, about noon, it was found that a fly and been left behind. The return voyage turned out to be long and difficult, on account of the lack of chart and compass, and because of the changed aspects of all coasts, the steadily rising water having submerged some of the lower landmarks and given to higher ones an unfamiliar look; but after sixteen days of earnest and faithful seeking, the fly was found at last, and received on board with hymns of praise and gratitude, the Family standing meanwhile uncovered, our of reverence for its divine origin. It was weary and worn, and had suffered somewhat from the weather, but was otherwise in good estate. Men and their families had died of hunger on barren mountain tops, but it had not lacked for food, the multitudinous corpses furnishing it in rank and rotten richness. Thus was the sacred bird providentially preserved.
Providentially. That is the word. For the fly had not been left behind by accident. No, the hand of Providence was in it. There are no accidents. All things that happen, happen for a purpose. They are foreseen from the beginning of time, they are ordained from the beginning of time. From the dawn of Creation the Lord had foreseen that Noah, being alarmed and confused by the invasion of the prodigious brevet fossils, would prematurely fly to sea unprovided with a certain invaluable disease. He would have all the other diseases, and could distribute them among the new races of men as they appeared in the world, but he would lack one of the very best — typhoid fever; a malady which, when the circumstances are especially favorable, is able to utterly wreck a patient without killing him; for it can restore him to his feet with a long life in him, and yet deaf, dumb, blind, crippled, and idiotic. The housefly is its main disseminator, and is more competent and more calamitously effective than all the other distributors of the dreaded scourge put together. And so, by foreordination from the beginning of time, this fly was left behind to seek out a typhoid corpse and feed upon its corruptions and gaum its legs with germs and transmit them to the re-peopled world for permanent business. From that one housefly, in the ages that have since elapsed, billions of sickbeds have been stocked, billions of wrecked bodies sent tottering about the earth, and billions of cemeteries recruited with the dead.”
10) Post-Ark Woes.
Again not that they could get to this point, but assuming all the other stuff somehow were possible and they landed the ark a year later fat, happy and not dead, there would be no food for the herbivores to eat, leading to their starvation, and no food for the carnivores to eat, save the herbivores. And only 2 of most of them, so each snack for a carnivore was an extinction event for a herbivore. And species in nature almost invariably go extinct when there are less than a few thousand of them, they don’t have enough biodiversity to compete with other species and their numbers spiral into oblivion in a phenomenon called “genetic meltdown”. Add to this noah’s burnt offering of “every clean animal” and it’s a wonder we have any animals at all.
11) Where’d the water go?
The bible just says the flood waters receded, but to where? They couldn’t go under ground, that is not possible. Some water can go somewhat under ground and some water vapor can exist in the atmosphere, but an ocean’s worth of water cannot go under ground any more than it can float in the air. It’s just not possible. Nor could it fly out into space, the earth is a gravity well.
The bible says the ark had a single window, about a foot and a half or so wide. That wouldn’t be enough ventilation to keep 2-7 of every plant species alive, let alone the animals, which produce huge quantities of C02, methane and other gases which are deadly without sufficient ventilation.
According to the biblical chronology the flood happened some 4400 years ago. If it had occurred it would’ve wiped out all of the ancient mesopotamians, destroyed egyptian society, killed off the native americans etc. But it didn’t. Because a global flood never occurred in that time frame.
In summation it’s also worth noting that it would be impossible in that day to actually know the world had flooded, since it would not be possible to travel to the far corners of the world to verify it, and that their concept of “world” was what they could see from the top of a large hill. They (including jesus) apparently had no idea how big the world was, which is why christ told his apostles in matthew 24 that the gospel message would reach all people in all nations of the world, he would return and all people in all nations would see him coming out of the clouds with angels, that it would be quickly followed by the end of the world, and all within one generation. Little did he know the world is a big, big place and everyone in the world can’t see anything, even day/night at the same time, and that a handful of people on foot wouldn’t be able to communicate the gospel to all people in all languages in a hundred generations, let alone 1 generation. The bible was written without a modern understanding of the world and it shows. These stories only make sense as either metaphors (which are sometime hard to see and often a bit of a stretch) or assuming a bronze age understanding of the world as a flat disk a few hundred miles long that water could easily drain off of the sides from after a global flood, and from which a single man could save all life by gathering up only the animals he knew about within walking distance from his home, and which could see jesus descend to earth with angels simultaneously because the earth is small and only has one side, and the gospel need only be taught to the romans and the greeks and those people they knew about.