Discoveries by a team of Romanian researchers regarding the largest lake ever to exist have earned a place in the Guinness World Records. The team, composed of researchers from the GeoEcoMar Institute and the University of Bucharest, revealed the immense proportions of the largest lake in the Earth’s history: Paratethys.
Guinness World Records has published an online article dedicated to ‘The Largest Lake Ever.’ Additionally, the record has been featured in printed editions in over 40 languages. The research aimed to illustrate how the European continent looked around 11 million years ago during the geological epoch known as the Upper Miocene. The most remarkable feature of the continent was likely Paratethys – a body of water stretching from the east of the Alps to regions that now belong to Kazakhstan, as stated in a press release by GeoEcoMar. Dan Palcu and his colleagues determined the proportions of the mega-lake in a study published in June 2021.
The study indicates that, at its peak, Paratethys covered an area of approximately 2.8 million square kilometers and contained over 1.8 million cubic kilometers of freshwater combined with saltwater in various proportions. This is over ten times larger than the combined volume of all current freshwater and saltwater lakes. ‘For a long time, it was believed that there was a prehistoric sea here, the Sarmatian Sea. Now we have clear evidence that for about five million years, this sea turned into a lake – isolated from the ocean and filled with animals not found elsewhere on the globe. The lake covered much of Romania, except for mountainous areas, leaving behind spectacular evidence such as the trovant sands in the Buzău Subcarpathians and Oltenia below the mountains, the limestones in the Istrița area, which 10 million years ago were tropical beaches, and the reddish cliffs in Southern Dobrogea, where the lake’s filling and drying cycles are reflected in the whitish-reddish alternations of the rocks,‘ said Dan Palcu, quoted in the statement.
The Paratethys megalake was characterized by a unique local fauna. During the most severe hydrological crisis, the megalake lost more than two-thirds of its surface and a third of its volume, with the water level dropping by up to 250 meters. This had a devastating impact on the fauna, and many species disappeared, including Cetotherium riabinini – the smallest whale found. In their research, Romanian scientists used a technique called magnetostratigraphy – using the record of the Earth’s magnetic field polarity reversals in rocks as a dating tool. To determine the size and volume of the Paratethys megalake, researchers resorted to digital paleogeographic reconstructions.
‘Our investigations go beyond simple curiosity. They reveal an ecosystem that responded dramatically to climate fluctuations. Exploring the cataclysms endured by this ancient megalake due to climate change provides invaluable information. With their help, potential ecological crises triggered by the current climate changes our planet is undergoing can be elucidated. At the same time, our research provides clarifications about the stability of basins with toxic waters, such as the Black Sea,’ said Dan Palcu. He explains that the modern Black Sea explains many environmental features of the ancient Paratethys.
Largely devoid of oxygen supporting life, the Black Sea’s depths harbor waters rich in hydrogen sulfide – a toxic gas harmful to both humans and most animal species. Moreover, Black Sea sediments contain ‘frozen’ methane, an exceptionally potent greenhouse gas that could be released into the atmosphere in response to global warming, triggering environmental catastrophes.
Currently, Dan Palcu’s team is researching the resilience of these ecologically fragile regions to climate change and human-induced modifications through a project funded by the National Recovery and Resilience Plan (PNRR).