What evidence is there that the Genesis/Noah Flood was global verses regional?

There is often broad skepticism voiced regarding the possibility of a global event known as the Flood. It’s not surprising; certainly one reason (which we’ve already discussed) is the need to depend on completely natural, undirected processes to create the fossil record we see. And, of course, as the Genesis Flood was a one-time-only event, there is simply no record of a repetition of that amazing event. All that said, there are several reasons why the Genesis/Noah Flood of Genesis should be considered global versus regional (local):

(1) All over the world, people had discovered fossilized animals and plants embedded in thick, sedimentary layers that were laid down by water. Sedimentary rocks are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles (detritus) to settle and accumulate or minerals to precipitate from a solution. Particles that form a sedimentary rock by accumulating are called sediment. Before being deposited, sediment was formed by weathering and erosion in a source area, and then transported to the place of deposition by water, wind, ice, mass movement or glaciers which are called agents of denudation.

Many of these rock strata were laid down very quickly, preserving various species and plant life. Based on evidence found in the Grand Canyon (covering an area of over 200,000 square miles) and in an area in Australia called Hawkesbury Sandstone, located outside of Sydney, just to mention a couple, many people think that a global flood is the only possible conclusion. Also, the Flood strikes at the argument for millions and billions of years necessary for evolution to do its work. The fossils found in the sedimentary rock of compressed sand, lime and mud are either the results of hundreds of millions of years of life and death and sediment, or the catastrophic impact of a global flood occurring over a period of the year (approximately 370 days) in which Noah and his family survived in the ark.

(2) The fact that Noah was commanded to build an ark to the dimensions that God commanded, and that God commanded two of “every” kind of animal to gather at the ark suggests the worldwide scale of the event. A regional flood would not have required every animal to come to the ark; they simply could have removed themselves from the area to be flooded. Remember that mankind was given 120 years to prepare for that moment, giving all those people ample time to relocate themselves away from Noah and his doomsday prophecies.

(3) There are over 500 flood myths found in the ancient literature of many people groups—literally found around the world, including stories from Mexico, Romania, India, and Sudan in east Africa. These myths share many common components in their stories to the extent that an appropriate question would be, “How could all these unrelated people groups have developed the same legend?” The only answer: a single common event.

(4) The words of God Himself: Then God said to Noah and to his sons with him: “I will establish my covenant with you and with your descendants after you and with every living creature that was with you—the birds, the livestock and all the wild animals, all those that came out of the ark with you—every living creature on earth. I establish my covenant with you: Never again will all life be cut off by the waters of a flood; never again will there be a flood to destroy the earth.” And God said, “This is the sign of the covenant I am making between me and you and every living creature with you, a covenant for all generations to come: I have set my rainbow in the clouds, and it will be the sign of the covenant between me and the earth. Whenever I bring clouds over the earth and the rainbow appears in the clouds, I will remember my covenant between me and you and all living creatures of every kind. Never again will the waters become a flood to destroy all life. Whenever the rainbow appears in the clouds, I will see it and remember the everlasting covenant between God and all living creatures of every kind on the earth”—Genesis 9:8-16. If the Flood was anything less than global, then God is a liar; obviously the floods that have occurred at the local level in the entire history of the planet since the Genesis Flood have destroyed much in the way of people and animals. The only event that has never occurred again is a global flood.

(5) New Testament scriptures: When Jesus was being asked by the Sanhedrin about when the kingdom of God would come, and continuing to discuss their question with His disciples, He said, Just as it was in the days of Noah, so also will it be in the days of the Son of Man. People were eating, drinking, marrying and being given in marriage up to the day Noah entered the ark. Then the flood came and destroyed them all. It was the same in the days of Lot. People were eating and drinking, buying and selling, planting and building. But the day Lot left Sodom, fire and sulfur rained down from heaven and destroyed them all. It will be just like this on the day the Son of Man is revealed—Jesus Christ, Luke 17:26-30. Jesus is describing, among other things, end times events that are intended for the entire world. Using the Flood in that discussion implies, like the end times, a worldwide event.
Likewise, the apostle Peter had this to say about the end times: First of all, you must understand that in the last days scoffers will come, scoffing and following their own evil desires. They will say, “Where is this ‘coming’ he promised? Ever since our fathers died, everything goes on as it has since the beginning of creation.” But they deliberately forget that long ago by God’s word the heavens existed and the earth was formed out of water and by water. By these waters also the world of that time was deluged and destroyed. By the same word the present heavens and earth are reserved for fire, being kept for the day of judgment and destruction of the ungodly—II Peter 3:3-7. Peter, like Christ, is drawing the comparison between the Genesis Flood and the coming judgment. If the point Peter is trying to make is the global scope of the judgment, then his using the Flood as a comparative is absolutely justified, since the scope of their reach is the same—global calamity, global impact.