Paratethys, the Largest Lake Ever to have Existed on Earth

Scientists have discovered that around 11 million years ago, Europe was home to the largest lake the world has ever seen.

Known as Lake Paratethys, it stretched from the Alps all the way to Central Asia, covering an enormous area of over 2.8 million square kilometers.

Dr. Dan Palcu of Utrecht University in the Netherlands led the research that revealed the true scale of this ancient mega-lake.

Using a technique called magnetostratigraphy, Dr. Palcu and his team analyzed magnetic reversals preserved in layers of sediment to precisely date the rocks and determine how Lake Paratethys formed and changed over time.

Their findings showed that as mountain ranges rose up in Central Europe, they cut off the ancestral Paratethys Sea from the global oceans, transforming it into a massive inland lake.

At its peak, Lake Paratethys contained over 1.8 million cubic kilometers of brackish water—that’s more than 10 times the volume of all modern fresh and saltwater lakes combined. Living in its waters was unique endemic wildlife like the tiny Cetotherium riabinini whale, the smallest ever found in the fossil record.

However, Lake Paratethys did not remain stable. Dr. Palcu’s research revealed it suffered multiple major droughts and hydrological crises over the millennia as the climate fluctuated.

During the most severe event, the mega-lake lost over two-thirds of its area and one-third of its volume, with water levels plunging by as much as 250 meters. This devastated the native species and drove many to extinction.

Eventually, Lake Paratethys reconnected with the emerging Mediterranean Sea, losing its title as planet Earth’s largest lake. But Dr. Palcu’s exploration of this ancient ecosystem has much broader significance beyond scientific curiosity.

By unraveling Paratethys’s dramatic response to past climate shifts, we gain invaluable insights that can help address modern and future crises, like the conditions found today in the Black Sea.

Originally cut off from the oceans around 6,000 years ago, the Black Sea now mirrors Paratethys’s toxic past. With little oxygen below, its depths harbor hydrogen sulfide gas which is harmful to humans and most sea life. Its shelf sediments also hold frozen methane—a potent greenhouse gas that could potentially flood the atmosphere if global warming triggers its sudden release, causing major environmental damage.

Through projects like this, Dr. Palcu aims to understand the resilience of such fragile regions to climate change and human impacts, so we can protect vital carbon stores and learn from history. His discovery of Lake Paratethys reminds us that even as we look to the past, the future depends on understanding Earth’s dynamic relationship with the climate.

Sources

Utrecht University | Palcu, D.V., Patina, I.S., Șandric, I. et al. Late Miocene megalake regressions in Eurasia. Sci Rep 11, 11471 (2021). doi.org/10.1038/s41598-021-91001-z