There are arguments defending the Genesis account of Noah’s flood. I wish to deal with them because they are almost comically stupid. The arguments attempt to reconcile the physical impossibility of Noah’s flood and the idea that it happened.
The reason the flood is impossible is that it depends on violations in the laws of physics. We know from the Genesis account that there are seas, land and mountains. The story is then of enough water being added to that system to raise the level of the seas to above even the highest mountain. That’s all the water in the seas plus more water, enough to flood the planet.
We know from climate science that if the ice caps melted and added that water to the system, and water were to expand slightly due to increased global temperatures we’d be looking at less than 20 feet of extra water. And that’s it; that is all the water in the global system. But the Genesis account of the flood depends on more than 8,800 feet of water being added. That is billions of litres of water, each millilitre being its own violation of the laws of thermodynamics.
There are two incoherent arguments to explain how this may have happened. One depends on a giant space-cloud that rained down on earth for 40 days at a rate of ~9’3” per hour, globally (making 8,800 feet in 40 days – just about submerging Mount Everest). That giant space-cloud would then itself have to be just short of 8,800 feet thick of homogenous liquid water forming a bubble around the earth, else a much thicker (80-90,000 feet thick) mist surrounding earth. Both are enough to block out all light to the earth*, thus no Noah; to have listened to a God; to have built the arc; to have written the story down.
*This is based on how much light penetrates our oceans. By the depth of 500 feet, even in very clear water, there is next to no light.
The second theory is that there was a store of water underground that erupted upwards to make the flood. This story has always been incoherent to me in that it necessitates both that the water flooded the earth and that the water reached escape velocity and immediately left the planet. Now, thunderf00t (a Youtube scientist) has provided the maths to prove that the water could not have reached escape velocity, so where is the water? Also, where is the nearly 9,000 foot deep cavity in the earth where all that water was stored before the event?
My favourite thing about these accounts, however, is neither their physical impossibility nor their failure to account for where the water then went. Instead, I like the fact that they both attempt to make the global flood-event a natural event; the theories negate the need for a God.
I’d like to offer some advice: when trying to account for the Genesis story of the flood do not try to explain how it happened; continue asserting God is supernatural and just made it happen. The burden of proof on your head is archaeological evidence that it ever happened: mass extinctions, oceanic sediments of the same age pretty much everywhere and littered with the fossils of land animals, aquatic erosion in places only wind erosion should have happened.
Once you’ve provided that we can start a discussion on what a ‘kind’ is, what the animals ate, how Noah got Marsupials and parasites and bacteria onto the boat when God never discusses so much as their existence let alone where to find them, and how all the animals immediately got placed in biogeographically suitable areas after the flood (and how biogeographically suitable areas could exist after a flood that should have destroyed all plant life and thousands of years of soil development everywhere).