New Geo-Archaeological Study Reveals 2,500 Years of Mediterranean Sea Level Fluctuations

The Templar palace ruins in Akko (Acre), one of the sites where a geo-archaeological study was carried out. New research finds that short-term rising and falling of sea levels may not say much about global warming patterns.

Rising sea level, one of many climate change-related phenomena expected to occur in the coming years, is a major environmental concern for many Middle Eastern countries where coastlines are long and water resources are scarce.

However, a recent study headed by Dr Dorit Sivan, Head of the Department of Maritime Civilizations at the University of Haifa, shows that showed that sea level rise (and fall) is nothing new “under the sun” here in Israel.  According to the study, the sea level in Israel has been rising and falling over the past 2,500 years, with a one-meter difference between the highest and lowest levels, most of the time below the present-day level.

“Rises and falls in sea level over relatively short periods do not testify to a long-term trend. It is early yet to conclude from the short-term increases in sea level that this is a set course that will not take a change in direction,” explained Dr. Sivan.

Dr. Sivan and research assistant Ayelet Toker set out to examine Israel’s sea level over the past 2,500 years, based on data deduced from many coastal archaeological findings.  The pair examined Crusader-era excavations from the Antiquities Authority in Acre, which revealed that the sea level during the Crusader period – just 800 years ago – was some 50-90 centimeters lower than the present sea level.  An analysis of other archaeological findings from the same period at Caesarea and Atlit reinforced this conclusion.

When additional sites were examined from periods before and after the Crusader period, Dr. Sivan and Ms. Toker discovered there have been significant fluctuations in sea level: During the Hellenistic period, the sea level was about 1.6 meters lower than its present level; during the Roman era the level was almost similar to today’s; the level began to drop again during the ancient Muslim period, and continued dropping to reach the same level as it was during the Crusader period, but within about 500 years it rose again, and reached some 25 centimeters lower than today’s level at the beginning of the 18^th century.

“Over the past century, we have witnessed the sea level in Israel fluctuating with almost 19 centimeters between the highest and lowest levels,” said Dr. Sivan.  “Over the past 50 years Israel’s mean sea level rise is 5.5 centimeters, but there have also been periods when it rose by 10 centimeters over 10 years. That said, even acute ups and downs over short periods do not testify to long-term trends. An observation of the sea levels over hundreds and thousands of years shows that what seems a phenomenon today is as a matter of fact ‘nothing new under the sun.’ ”

However, although rising sea level may not be new, it may still be incredibly destructive.  Impacts like flooding, underground water salinization, flooded effluents, and acceleratead coastal damage are all associated with sea level rise.  Israel and other nearby Mediterranean countries should therefore make every effort to prepare for and adapt to possible damage in the coming years.

:: University of Haifa

Photo Credit:  Amir Yurman, University of Haifa

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