Washington, Jan 27 (Inditop.com) Rising and falling sea levels over relatively short periods do not indicate long-term trends, a new study says.
“An assessment of hundreds and thousands of years shows that what seems an irregular phenomenon today is in fact nothing new,” explains Dorit Sivan, who supervised the study at University of Haifa, Israel.
Rising sea level is one of the phenomena that have the most influence on humankind: It not only floods the littoral regions but also causes underground water salinisation, flooded effluents and accelerated coastal destruction.
The study has found that the sea level in Israel has been rising and falling over the past 2,500 years, with a one-metre 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,” explains Sivans, who is head of the department of maritime civilisations at Haifa.
The changing sea level can be attributed to three main causes. The first one is the global cause – the volume of water in the ocean, which mirrors the mass of ice sheets and is related to global warming or cooling.
Secondly, the regional cause – vertical movement of the earth’s surface, which is usually related to the pressure placed on the surface by the ice; and third the local cause – vertical tectonic activity, points out Sivan, according to a Haifa release.
Seeing as Israel is not close to former ice caps and the tectonic activity along the Mediterranean coast is negligible over these periods, it can be concluded that drastic changes in sea levels are mainly related to changes in the volume of water.
