A land bridge connecting Europe and Africa might still exist if not for the disaster that helped “rebirth” the Mediterranean.
According to a recent study published in the scientific journal Nature Communications, the Mediterranean Sea literally dried up about 5.5 million years ago, losing up to 69% of its water compared to what we see today.
Evidence for this frightening event was revealed by a research team led by Earth system scientist Giovanni Aloisi from the French National Centre for Scientific Research (CNRS) through an analysis of chlorine isotopes in salt deposits on the seabed.
The Mediterranean nearly disappeared 5.5 million years ago – (Photo: Pibernat/Garcia-Castellanos).
Combining the construction of models and numerical simulations, the authors pointed out that this event – known as the Messinian Salinity Crisis (MSC) – occurred in two phases.
The first phase involved 35,000 years of limited water flow between the Mediterranean and the Atlantic Ocean, through what is now the Strait of Gibraltar.
As seawater was not replenished with fresh water, the processes of salt deposition and evaporation in the Mediterranean were accelerated.
In the second phase, lasting the next 10,000 years, the Mediterranean Sea became completely isolated. In some areas, the water level may have dropped by up to 2.1 kilometers.
During this second phase, the underwater land bridge crossing the Strait of Sicily emerged, dividing the Mediterranean and creating a land bridge connecting Africa and Europe.
This led to a faster evaporation rate in the eastern Mediterranean, where sea levels dropped most significantly, leaving behind numerous large salt deposits.
Scientists have long debated how the MSC occurred and whether it happened when the Mediterranean was completely separated from the Atlantic.
This new study suggests that both perspectives are correct and that it was a two-stage process.
The researchers did not delve into why the Mediterranean became isolated, but this period fell within the Middle Pleistocene of the Quaternary period, a time of significant and widespread tectonic activity.
Thus, it is possible that these geological activities inadvertently caused changes to the topography and restricted the flow between this sea and the Atlantic.
The MSC itself would cause even more upheaval, as pressure increased on the surface crust and surrounding areas dried out.
“The massive size of the Mediterranean basin due to the lowered water level would cause climate impacts on a global scale, including changes in rainfall patterns” – the authors explained.
Today, the Strait of Gibraltar is much wider and deeper than during the first phase of the MSC. Without this connection to the Atlantic, it is estimated that the current sea level in the Mediterranean would be dropping by nearly half a meter each year.
We still have the Mediterranean today thanks to a “great flood” event that occurred just after that dry period, known as the Zanclean Flood, which happened about 5.33 million years ago and quickly filled the sea while reconnecting it with the Atlantic.
