00:00About 5.3 million years ago, a major event radically remodeled the Mediterranean basin.
00:07A terrible flood re-supplied the sea, which until then was as salty as sterile.
00:13This event, called the Zanclean Transgression, forever altered the geography of the region.
00:20The Mediterranean Sea, surrounded by Europe, Africa and Asia, is reconnected to the Atlantic Ocean by the Strait of Gibraltar.
00:28This narrow passage measures about 13 km.
00:31Although it is not very wide, the strait plays a crucial role in balancing the water masses between the two streams.
00:38About 6 million years ago, various factors were able to isolate the Mediterranean from the Atlantic.
00:44Some evoke a glacial period, while others speak of tectonic movements, such as earthquakes.
00:50Whatever the cause, it led to the so-called Messinian salinity crisis.
00:56For about a thousand years, the sea slowly evaporated, leaving behind a dried up basin, located several kilometers below sea level.
01:05This crisis profoundly altered the landscape, creating conditions similar to those of the current dead sea.
01:11This means that the luxurious beauty of the Mediterranean outskirts was once an extremely salty environment.
01:17A salinity nearly ten times higher than that of the ocean.
01:21If you had the opportunity to visit this place, you could easily float on the small amount of water available.
01:27And without even being a seasoned swimmer.
01:29The high concentration of salt and minerals would have made survival difficult for most creatures.
01:35However, some robust microorganisms, such as bacteria, could not have adapted to these extreme conditions.
01:41Nowadays, at the bottom of the Mediterranean Sea, there are caves as impressive as the Grand Canyon.
01:47These formations seem to date from the period of dehydration mentioned above.
01:51Traces suggest that large rivers, such as the Nile and the Rhône, flowed directly into the Mediterranean at this time,
01:59digging deep canyons several thousand meters below sea level.
02:04At the time, people were looking for explanations for the drying up of the Mediterranean and invented all kinds of myths and legends.
02:13One of these stories comes from the inhabitants of the south of Iberia, which today corresponds to Spain and Portugal.
02:19This myth, also reported by the famous writer Plin the Elder,
02:23tells that the Mediterranean was once isolated from the ocean,
02:26until the hero Heracles, endowed with superhuman strength,
02:30made his way to the Garden of the Hesperides, through Gibraltar's current rock.
02:36This journey allowed the oceanic zoos to invade the Mediterranean,
02:40transforming it into the sea we know today.
02:44Some fossils also seem to corroborate the exceptional magnitude of this flood.
02:49Remnants of marine organisms have been discovered in layers well above the current sea level,
02:54indicating that these areas were once submerged.
02:57The fossils found include molluscs, fish and even marine mammals.
03:02Thanks to modern techniques, we now have an estimate of the moment when the Zanclean Transgression occurred.
03:08Researchers have used computer simulations to reconstruct this event,
03:13thus providing additional proof of its reality.
03:16They have also discovered that it was possible that the Mediterranean was undergoing new changes.
03:21Gibraltar's strait could close again, probably due to deep tectonic movements.
03:26This could lead to a new drying up of the Mediterranean over a period of about a thousand years,
03:31and if the African continent continues to move north and draws closer to Europe,
03:36the Mediterranean basin could even disappear entirely.
03:39One of the most famous major floods, albeit hypothetical, is that of the Black Sea.
03:44According to some scientists, about 8,400 years ago,
03:48the Mediterranean water could have overflowed into the Black Sea through the Bosphorus strait.
03:53This overflow could have caused a huge disaster,
03:56forcing the populations living around the Black Sea to leave their homes
04:00and move further into the lands of the European and Asian continents.
04:04These migrations could have favored the propagation of the stories relating to the cataclysm.
04:09The researchers who formulated this hypothesis also suggest that these migratory populations
04:14could have introduced new agricultural methods into their home lands.
04:18However, not all scientists are convinced.
04:22Some believe that, if an inundation did indeed take place,
04:26it occurred earlier and was much less significant.
04:30They do not think that this event could have inspired the story of Noah's Ark, for example.
04:35According to this myth, a very pious man would have been warned by God in person
04:39of the arrival of a prodigious flood.
04:42To save all living species, he would have gathered couples of animals
04:46and would have embarked them on a large ark.
04:49Some researchers also fear that getting too close to the true floods of ancient legends
04:54could end up blurring the boundaries between science and belief.
04:58There could be other explanations for the fact that the myth of the flood
05:02appears so frequently in different cultures around the world.
05:05One of the hypotheses is that these floods were absolutely devastating for the first farmers,
05:10pushing them to imagine myths that preceded the end of time.
05:14Another theory suggests that the discovery of fossils of marine creatures in incongruous places
05:19would have given birth to this belief in a great historical deluge.
05:23The parade of future floods could reside in floating cities.
05:28With the continuous elevation of the sea level, coastal cities such as Amsterdam,
05:32New Orleans and Venice may find themselves submerged.
05:36Floating infrastructures could then offer a viable solution
05:39and buildings capable of rising with the water level,
05:43while resisting extreme climatic conditions.
05:46The Netherlands, which has a long tradition of managing water-related risks,
05:50is at the forefront of these floating innovations.
05:53Faced with the exhaustion of the space available for urban expansion,
05:56we could be led to live on the waves.
05:59This adaptation would reduce the density of our populations
06:03and explore innovative agricultural methods such as floating gardens.
06:08In addition, these habitats could offer interesting energy alternatives
06:13thanks to the exploitation of solar and wind energy,
06:17while being potentially more economical in the long term.
06:20Such a floating city could soon see the light of day in the Maldives.
06:24This project aims to accommodate up to 20,000 people
06:27and will include residential and restaurant spaces, as well as shops and schools.
06:32Designed to imitate the shape of coral,
06:35the city will have canals arranged between nearly 5,000 floating islets.
06:40Construction will be carried out from modular units
06:43assembled on a construction site nearby.
06:46Once ready, these units will be towed up to the floating city.
06:50The next step will be to attach these units to a large core of submerged concrete,
06:55solidly anchored to the seabed thanks to steel pilots.
06:58This configuration will allow the modular units to move fluidly,
07:02in harmony with the movements of the sea.
07:04And for those who fear being sick,
07:06the surrounding coral reef will serve as a natural breakwater to mitigate the waves.
07:11Artificial coral banks will also be placed under the city,
07:15which will also help the coral to grow naturally.
07:18The long-term goal is to make the facility autonomous.
07:21It will have electricity mainly from the solar energy on site.
07:26Waste will be treated up close and reused as fertilizer for plants.
07:31Instead of air conditioning, the city will use deep-water cooling.
07:36This method pumps cold water from the depths of the sea to cool the area,
07:40thus saving energy.
07:42The Earth is not the only planet to have experienced major floods.
07:46Mars, in ancient times, also seems to have been affected by cranes,
07:51which played a significant role in the formation of its surface.
07:55Recent research reveals that several billion years ago,
07:58Mars underwent major flooding,
08:01contributing to the formation of its valleys and canyons.
08:05These floods were caused by heavy rains,
08:08which quickly changed the landscape of Mars,
08:10sometimes in a few days or weeks.
08:12Unlike the Earth, where rivers form slowly,
08:16floods on Mars have caused rapid changes,
08:19especially around 4 billion years ago.
08:22Although we have known for some time that there have been floods on Mars,
08:26this study has revealed their real extent.
08:29We now know that they were more extensive and frequent
08:32than we had previously believed.
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