The Mediterranean Sea lost almost all of its water, triggering a global crisis

About 6 million years ago, an extraordinary event occurred that restructured the Mediterranean and its water. This phenomenon, known as the Messinian Salinity Crisis, transformed the sea into a massive salt basin.

But how did a million cubic kilometers of salt come to rest in such a short time on the Mediterranean seabed? Until now, that remained a mystery.

Now, scientists have made a significant breakthrough. By analyzing chlorine isotopes found in the salt on the Mediterranean seabed, they’ve unveiled the two distinct phases of this intense evaporation event.

Phases of desiccation and salt accumulation

The first desiccation phase lasted approximately 35,000 years. During this time, salt deposition occurred exclusively in the eastern Mediterranean. This was due to a restriction of the Mediterranean outflow into the Atlantic, resulting in a brine-filled basin in the east.

The second phase, however, was a different story altogether. Over less than 10,000 years, salt accumulation took place throughout the entire Mediterranean.

An expeditious evaporative event caused such a sharp decline in sea-level – 1.7-2.1 kilometers in the east, and approximately 0.85 kilometers in the west – that the Mediterranean basin lost up to 70% of its total water volume.

Moreover, change on such a monumental scale didn’t occur without repercussions. The effects of the spectacular fall in sea level were far-reaching and not just limited to the marine environment itself.

Factors linked to Mediterranean water loss

Local volcanic eruptions may have been triggered due to the release of pressure on Earth’s crust. These eruptions could be thought of as Earth’s reactions to the rapid loss of such a substantial amount of water weight.

Moreover, this large scale evaporative event also might have influenced global climate patterns. The drastic depression caused by the sea-level drawdown rippled outwards, affecting weather systems far and wide.

These results point towards a better understanding of not just the Messinian Salinity Crisis, but also of the ways extreme desiccation events can drastically alter ecosystems and climates on a global scale.

In the last moments of this salinity crisis, the sea-level of the Mediterranean was almost a kilometer below that of the Atlantic Ocean. This extreme difference lead to the eventual collapse of the Strait of Gibraltar.

Mediterranean water loss and marine life

The Messinian Salinity Crisis also posed significant challenges for marine life in the Mediterranean basin.

The extreme hypersaline conditions would have been inhospitable for most marine organisms, leading to mass extinctions of species that could not adapt.

However, evidence suggests that some extremophilic organisms (organisms capable of surviving in highly saline environments) managed to persist during this period.

Fossil records indicate that isolated pockets of less saline water, or refugia, may have existed, providing temporary habitats for certain species. These pockets paint a picture of resilience amidst an environment of extreme ecological stress.

Restoration of the Mediterranean water

The collapse of the Strait of Gibraltar acted as a gateway for the Atlantic Ocean to flow back into the Mediterranean. This sudden influx of water ended the prolonged desiccation, refilling the Mediterranean basin and restoring its water levels.

As a result, the Mediterranean transitioned from a nearly dry, hypersaline basin dominated by thick salt deposits into a thriving open sea once again, with normal marine conditions and ecosystems returning over time.

This event marked the resolution of the Messinian Salinity Crisis, reshaping the region’s geography and ecological dynamics permanently.

Modern climate challenges

The insights gained from studying the Messinian Salinity Crisis carry valuable lessons for our understanding of current and future environmental changes.

This event showcases how rapid geological and hydrological transformations can trigger cascading effects on the climate, ecosystems, and even tectonic activity.

Contemporary concerns about rising temperatures, altering precipitation patterns, and water scarcity echo some of the climate disruptions that may have been felt during the crisis.

By learning from this historic event, scientists emphasize the importance of global collaboration and sustainable resource management to mitigate the impacts of looming environmental challenges on both natural systems and human societies.

Significance of the study

This research on the history of Mediterranean water has provided fresh insights into historical geological events, enhancing our comprehension of these past occurrences.

By examining these findings, scientists and researchers have the opportunity to improve their predictions about future geological phenomena.

Understanding the patterns and causes of past events allows for better preparation and response strategies, potentially reducing the adverse impacts of similar events that may occur in the future.

Learning from geological history

The study emphasizes the importance of learning from past geological activities to make informed decisions that safeguard communities and environments against natural disasters. It raises a critical question: will we apply the lessons learned to protect our future?

The findings from the study serve as a call to action, urging society to integrate historical lessons into future planning and preparedness efforts.

The study was led by G. Aloisi, a scientist at the French National Centre for Scientific Research (CNRS), which is one of the largest governmental research organizations in France.

The study is published in the journal Nature Communications.

Image Credit: Pibernat & Garcia-Castellanos

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