Imagine that the Mediterranean Sea suddenly rose two meters in height within a short time. The beach of Tel Aviv would be wiped out, parts of the city and all the other coastal Israeli cities would be flooded and wells and underground aquifers would become salty.
Fortunately, this is science fiction, but there actually was a drastic rise of two meters in sea level over a short period of about 200 years along what is now the Israeli coastline – about 2,000 years ago, in the transition between the Hellenistic and Roman periods, according to a new study just published in the prestigious journal PloS [Public Library of Science] One under the title “New relative sea-level indications from the Eastern Mediterranean: Middle Bronze Age to the Roman period archaeological constructions at Dor, the Carmel coast, Israel.”
It was carried out by an international team led by researchers that included Prof. Assaf Yasur Landau, head of the Recanati Institute of Marine Studies at the University of Haifa, and included colleagues from the (Catholic) University of San Diego in California, the University of Bologna and the Italian National Institute of Geophysics and Volcanology.
The study sought to trace the impact of rising sea levels on coastal cities in ancient times and processes of loss of marine and coastal infrastructure due to rising levels. The researchers focused on excavations mainly in Tel Dor, a port city that existed from the Middle Bronze Age, about 1,800 BCE to the Roman period in the Land of Israel, about 200 CE.
The researchers examined remains of buildings in the port city above and below sea level. “This is the first time that evidence of such a drastic increase in such a short period has been discovered in the historical period,” said Yasur Landau.
“It is an increase that is recognized only when talking about the end of the ice age and the great melting of glaciers. We find an increase of more than twice the dangerous increase we are talking about today, “said Prof. Thomas Levy of the University of California at San Diego who participated in the study. Prof. Dorit Sivan, co-leader of the study, also from the Recanati Institute of the University of Haifa, added that “this is the first study examining sea level changes from the Iron Age to the present day in our area, a period until now there was almost no evidence of sea level changes.”
“The location of the Israel coast, at the very eastern edge of the Mediterranean and a land bridge between Egypt and Southwest Asia, makes the area ideal for connectivity by both land and sea,” they wrote. “Adaptation to coastal residence using the coastal aquifer and maritime resources and later maritime connectivity and trade began in the Neolithic period and continued into the Bronze Age. This left a rich record of submerged and coastal settlements from the 8th to 2nd millennium BCE, which had first negotiated the challenges of climate changes, rising sea levels, but then were severely impacted by the turmoil of the Bronze Age World System collapse. Coastal habitation recovered during the Iron Age, 1200-530 BCE, with the earliest examples of harbor construction appear in the sites of Dor. The inclusion of the area into the Hellenistic cultural sphere and later the Roman empire further strengthened the coastal sites, with many, such as Akko, Dor, Caesarea and Ashkelon, growing in size and importance.”
Yasur Landau explained what that drastic rise would have looked like: “We found underwater the base of the wall and sea gate of the Iron Age, which were certainly supposed to be on dry land. This means that when they were built, the water level was low compared to today. From the Roman period and even today, this receives water from the sea and reflects a water level similar to today, about two meters high.”
From historical and archaeological evidence, scholars know that some Hellenistic coastal cities in Israel experienced a decline or even abandonment in the transition between the end of the Hellenistic period and the transition to the Roman period, around 30 BCE. “We have seen similar evidence of a decline in Acre and other Hellenistic coastal cities, and we speculate that the area’s inhabitants, seeing entire buildings gradually covering the water, identified the rapid rise in sea level. But in many cases, they failed to adapt to the new conditions successfully,” said Dr. Gil Gambash, a University of Haifa historian who participated in the study.
The team said it was hard to know what caused the abnormal phenomenon. “Despite the Law of Basic Hydraulics, sea level rise is not necessarily similar even in nearby areas. Faced with this drastic rise, there may have been shorelines in other places that actually experienced a large drop in level. We don’t know of a special event at this time that can explain the phenomenon. Clearly, the geography, economy and lifespans all have changed drastically in this relatively short period beyond the Hellenistic and Roman periods in the Land of Israel,” the researchers concluded.