It was until recently that I assumed that most regarded the literal account of this tale as such: a myth, nothing more. However, to my dismay, I encountered a shocking statistic: 61% of Americans in 2004 believed the story of Noah's Ark and the Global Flood literally happened. Although this statistic was from 9 years ago, I'm fairly confident that it hasn't fluctuated significantly in under a decade, unless, of course, the majority of the American public have actually become informed about major Biblical flaws (Yahweh forbid).
I shall hence categorically and comprehensively deconstruct and analyse the Genesis Flood Account as if it were a literal event, and not, I must emphasise, a symbolic account. So yeah, you can put those strawmen back into their cases.
The Account
First of all, the actual story, from Genesis 6:9-22, Genesis 7 and Genesis 8: 1-21.
Water: A lot of it
The first problem demonstrated by this account is water, or rather, the sheer quantity of it. The account explains how "all the high mountains under the heavens were covered", which, of course, implies that the water level was higher than Mount Everest, the Earth's highest mountain. Taking into account that the surface area of the Earth is 510 million kilometres, and acknowledging that the height of Mount Everest is 8.848km , we can perform as basic volume calculation, revealing that the total volume of water required to flood the Earth to such an extent is 4,512,480,000 cubic kilometres of water. In comparison, the present volume of water on the Earth (i.e in oceans, lakes etc) is 1,338,000,000 cubic kilometres, meaning that approximately 3.4 times the Earth's current water volume came out of absolutely nowhere. That's right, nowhere.
That's not all of it as well. The account details that the flooding process occurred for "forty days", meaning that approximately 112,812,000 cubic kilometres fell per day, 4,700,500 per hour, 78,342 per minute and 1306 per second. At any one time, the Earth's atmosphere holds approximately 12,900 cubic kilometres of water, which means that during the flood, approximately six times the Earth's atmosphere's water volume was falling every minute.
Of course, there's also the problem of where 4.5 billion cubic kilometres of water actually went. The floodwaters began to fall on the 17th day of אייר or "Iyyar", a 29 day month, and had fully receded by the 27th of that month one year afterwards. This puts the duration of the flood at 394 days, allowing us to calculate that it took 204 days for the waters to fully recede. This means that at a rate of 22,120,000 cubic kilometres per day, this water was evaporating into the atmosphere. However, the Bible offers no explanation where this water 34,980 times the average volume of water in the atmosphere actually went. Did it dissipate into space? Improbable, considering that the occasional water molecule only ever leaves the atmosphere to space by being broken into its respective hydrogen and oxygen atoms by ultraviolet radiation; a process almost completely stopped by the Earth's protective ozone layer. The atmosphere would no doubt be unable to cope with that volume of water, condensing and thus creating even more precipitation in an endless cycle.
Essentially, unless we disregard the fact that the atmosphere can't physically contain that volume of water without it falling as rain, the water vapour present would render the air unbreathable, as well as cause global temperatures to plummet by reflecting the sun's rays.
The Ark
Noah was instructed to construct his "Ark" based on an archaic unit of measurement known as the cubit. There are several variants of the cubit, the Biblical one being the "Near Eastern Cubit", which is approximately 18 inches (around 0.45 metres). The Bible states that the Ark was "three hundred cubits long, fifty cubits wide and thirty cubits high." Converting these into modern metric measurements, the ark was 135x22.5x13.5 metres. Noah is also instructed to make the ark out of "cypress", a reference to a family of conifer trees known as "Cupressaceae", and despite specifying what type of wood it was to be made out of, made no plans for a rudder or any other type of steering mechanisms. So, in summary, God instructed Noah to construct a ship 135 metres long, made of wood, with no method for steering at all, and this ark was to carry every animal species in existence.
By way of comparison, a modern Nimitz aircraft carrier is 332.8 metres long and can carry up to 90 aircraft, despite being over 2.5 times the size of this legendary ark. Not only that, but constructing the ark out of wood makes it relatively flimsy in comparison, and combined with the lack of a steering mechanism, it's fair to say that the ark wouldn't have lasted long as the Earth rapidly flooded in what would have resulted in intense storm waters.
Animals
Having touched on animals in my last section, I shall go into greater detail here. As of 2010, there were 1.7 million known animal species, and the number has no doubt increased over the past 3 years. In fact, it is estimated that there are over 8.7 million non-bacterial species in the world today. Of course, this raises numerous problems for the feasibility of the story once this is put into perspective, and numerous questions are raised.
Firstly, how did Noah collect "two of all living creatures" of approximately 8.7 million animal species? Assuming, of course, we're not ignoring the fact that God instructed Noah to "bring" them onto the ark himself, contrary to the belief that they actually came to Noah of their own will (which still has several problems I'll discuss soon).
Assuming Noah actually did collect 8.7 million species, not only does it mean he was the discoverer of the Americas, but in fact he was the greatest zoologist to have ever lived.
This man, in his early 600s, would have had to immobilise polar bears and transport them from the arctic to an isolated area in ancient Mesopotamia. Even if this process took 100 years, and Noah spent this entire time without any sleep (the average human will last 2 weeks before dying of sleep deprivation), he would have had to collect 238 species per day or 10 new species per hour, something not physically possible considering the time required to both travel to the location of these species and capture them (assuming none were hostile and decided to kill Noah, which many of them would have).
However, if we assume that Noah didn't collect all of the animals himself, numerous problems are still posed; for example, how did sloths travel 12000 kilometres (as the crow flies) from Central America to the area of modern-day Iraq. As comical as the idea is of a sloth, a famously slow and lazy animal, traversing the Atlantic Ocean, it frankly remains nonsensical to suggest a sloth could do so. On the other hand, one could suggest the sloth travelled up into Alaska to Chukotka (still required to traverse some water) in conditions considerably colder than what it is acclimatised to, without any of its natural habitat or nutrition, meaning that it would die pretty quickly.
In addition, many species will have had to have been collected hundreds of times, in order to provide food for the carnivorous species on the ship, which goes directly against God's commands to only take two of each species on board. Noah would have also had to cater for the specific survival needs of every animal on his vessel, providing the exact dietary requirement for 8.7 million species whilst keeping the vessel at a temperature they can survive in, which is something that would no doubt be difficult to achieve considering the 135 metre-long wooden vessel wouldn't have contained the necessary means to control said temperature for every single animal.
It's also worth noting that the Bible assumes that all species possess both male and female variants, something which is demonstrably false. By saying so, the Bible demonstrates that it knows nothing of hermaphroditic species or those capable of performing autogamy (or self-reproduction), and thus highlights the Bible's complete lack of understanding about basic biology, suggesting that it is less of the work of a divine being but rather a fallible human author from no earlier than 1500 bc.
Such technicalities aside, let's just put this into perspective: the absolute maximumvolume of the ark was 41006.25 cubic metres (based on the previous measurements), and this is assuming that the ark was a perfect box shape. Now, taking into account 2x8.7 million=17.4 million (2 of every animal), we can work out approximately how much space each animal had, if (and that's a big "if") we ignore the living room for Noah, his family and 394 days worth of supplies for these animals. Dividing the volume by the number of animals, we work out that the volume per animal would come to approximately 0.0024 cubic metres. So, assuming Noah did manage to get every animal on board, they would've either died of suffocation or being crushed.
What about the plants?
As I'm sure you'll notice from reading it, the Genesis Account makes no reference to what happened to plant life during the flood. Unless Noah collected all plant life on Earth, which is even more ridiculous than him storing all animal life, we can assume that the account implies that plants remained relatively unaffected by the floodwaters, managing to survive over a year submerged 8.8km beneath the water level. Of course, to believe that this was possible essentially requires you to know nothing about basic plant biology.
Firstly, terrestrial plant life is enabled to perform its basic functions through gaseous exchange, using its stomata to absorb carbon dioxide for photosynthesis, allowing it to produce vital glucose for aerobic respiration. Aquatic plants, however, absorb carbon dioxide that is dissolved in water in four forms: carbon dioxide, carbonic acid, and carbonate and bicarbonate ions. Due to a notable difference between water and air carbon dioxide levels (i.e water has considerably less carbon dioxide than water), combined with terrestrial plants' lack of adapted exchanged surfaces to absorb carbon dioxide from the water, photosynthesis couldn't continue, at least at a rate that would allow the plant to survive for over a year.
Secondly, even with sufficient carbon dioxide, plants still require light to photosynthesise. Of course, light levels decrease substantially the further down one goes through the aquatic layers. If we compare the approximate depth of water at the time of the Flood with an actual location, the Puerto Rico Trench would be suitable, an oceanic trench with a depth of 8.8km. This depth in standard terms of aquatic layers is known as the "Hadal zone", which begins at depths of 6km and greater. In terms of the other layers, the Mesopelagic, the zone between 200 and 1000 metres, still doesn't receive enough light necessary to allow photosynthesis to take place. In the Hadal Zone (or Hadopelagic), sunlight is completely absent, making photosynthesis impossible.
If that isn't enough to convince you, the pressure of the Hadal Zone can reach around 1100 atmospheres (i.e. 1100 times standard atmospheric pressure). Such a pressure would completely crush the plants, effectively destroying them regardless of the limiting factors of photosynthesis.
So, in summary, as a result of a lack of carbon dioxide, light and immense pressure, the Global Flood would have completely eradicated all plant life on Earth. Still, that didn't stop Noah's dove from bringing him back a "freshly plucked olive leaf", did it?
Repopulation
If we somehow ignore the fact that, at this point, the Earth should be a wasteland devoid of plant life and the air should be saturated with water vapour to the extent that the air is unbreathable, and we excuse the fact that Noah had beat the impossible odds of collecting 8.7 million animal species and they weren't crushed to death on his wooden vessel that couldn't be navigated, we have to recognise that they would have to return to where they came from, despite being in the middle of ancient Mesopotamia.
Take, for example, the Walrus; there are only two in existence as of the Flood's end. It doesn't exactly take a zoologist to recognise that walruses aren't exactly adapted to traverse arid environments; in fact, quite the opposite. The walruses' lack of mobility (due to their immense bulk) combined with a lack of natural prey and overheating in post-flood Mesopotamia would result in the walrus' extinction. I can confirm that as of 2013, living walruses still exist.
In fact, all land carnivores would've died out within a day or two, due to a complete lack of nutrition. Those who argue that carnivores suddenly started consuming plant material, clearly don't understand that they can't efficiently digest plant material, many even not being able to digest it at all.
Only the few herbivorous or omnivorous animals lucky enough to be adapted to the Near East environment could have possibly survived to repopulate; once again assuming that all plant life wasn't completely destroyed. Still, the chances of fully repopulating with only two members of the species is incredibly slim, as one death would've resulted in that species' extinction.
So, that's it, the Global Flood as described in Genesis could not have happened. I probably could've stopped after the first point, as one point in this entire argument is enough to prove that such an event is impossible: however, explaining several issues with the story helps to explain how it is wrong on almost every conceivable level. If the 61% actually read this argument (or similar ones, for that matter), I'm certain that at least the majority of them would see reason and accept the impossibility of the Genesis Flood Account.
So, do you believe the Genesis Flood Account, or have you ever in the past? Feel free to point out anything I missed.