In the last ice age the upper Midwest of North America was covered with ice a mile thick in some places. You think Chicago is cold now? When that ice age ended as the earth’s climate warmed the melting ice gave rise to sea level making what we now call England into an island. Before that there was no English Channel, England and Europe were connected. The upper Midwest of North America became ice-free and the Great Lakes were formed. Several places now under the sea, especially on the European side of the Atlantic, were previously inhabited by humans. They were flooded out of their homes.
It was not a catastrophe. When the last ice age ended about 12,000 years ago it took over a 1,000 years for the ice to melt and the sea level to rise. That’s about 50 human generations. The Indians inhabiting North America no doubt rejoiced at all the new lands that were opened to them. The ones who had not yet migrated from Asia were stuck where they were. The land bridge across the Bering Sea was now under water. Unlike the ancient Polynesians they had not learned to navigate oceans.
The Mediterranean Sea as we know it today similarly formed about 5 million years ago when Atlantic Ocean waters breached the strait of Gibraltar, sending a massive flood into the basin.
This was the Pliocene age in the Cenozoic Era of geologic time.
The Mediterranean basin must have been something that would make the Grand Canyon look like a hole some kids might dig in a back yard, for the sea that fills it today is over 17,000 feet deep at it’s greatest depth. In its deepest part it must have been Death Valley multiplied by one hundred.
There weren’t any humans in the Mediterranean basin before the flood, since there weren’t any humans anywhere on earth at that time. There were, however, many of the same animals living today. The beginning of the age of mammals preceded this time by millions of years. There were also birds and reptiles galore. Many of these no doubt lived in the Mediterranean basin before the flood. Unlike the flood caused by the melting of ice just 12,000 years ago, the Mediterranean canyon filled up with water very quickly, perhaps in as little as 2 years. That was still enough time for most of the animals to escape although many probably could not adapt to the new conditions and thus went extinct.
Some people are today worried about the catastrophe that climate change might bring. The first thing to know it that climate change has happened many times on this earth and none of it has had anything to do with human activity. There will be future climate change, without a doubt. It’s a stretch from fact to myth to blame it on humans though. The earth has shown many times that it is perfectly capable of changing its climate without any human intervention. It may have something to do with the Sun.
For some very interesting reading on this and similar subjects I highly recommend this.