The rising sea level is one of the phenomena that have most influence on humankind: the rising sea not only floods the littoral regions but also causes underground water salinization, flooded effluents, accelerated coastal destruction, and other damage.

According to Dr. Sivan, the changing sea level can be attributed to three main causes: 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; 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 the local cause -- vertical tectonic activity. 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 Israel's sea levels are mainly related to changes in the volume of water.

In the present study, in light of earlier studies, research student Ayelet Toker and Dr. Sivan, set out to examine Israel's sea level over the past 2,500 years, based on data deduced from many coastal archaeological findings. They made a careful selection of findings that have been reliably and accurately dated, and first focused on findings that were excavated by the Antiquities Authority in Acre of the Crusader period. These revealed that the sea level during the Crusader period -- just 800 years ago -- was some 50-90 centimeters lower than the present sea level.

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, it was revealed that 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 18th century.

"Over the past century, we have witnessed the sea level in Israel fluctuating with almost 19 centimeters between the highest and lowest levels. 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," Dr. Sivan concludes.

NOAA’s Fisheries Service has issued regulations and a letter of authorization to the U.S. Navy that includes measures to protect marine mammals while conducting naval exercises off the Gulf of Mexico coast. The regulations require the Navy to implement measures designed to protect and minimize effects to marine mammals.

(From NOAA) -- The Navy requested authorization for the activities under the Marine Mammal Protection Act because the high- and mid-frequency sound generated by sonar, and the sound and pressure generated by detonating explosives, may affect the behavior of some marine mammals or cause a temporary hearing loss.

NOAA’s Fisheries Service does not expect the test and evaluation activities to result in serious injury to marine mammals. However, NOAA is requiring the Navy to use mitigation measures because exposure to nearby underwater detonations can injure marine mammals, and some injury could occur despite the Navy’s best efforts. The proposed authorization allows for a small number of incidental injuries to marine mammals.

NOAA’s Fisheries Service has determined that these effects would have a negligible effect on the species or stocks involved.

Under the authorization, the Navy is required to follow mitigation measures to minimize effects on marine mammals, including:

• establishing marine mammal safety zones around each vessel using sonar and during underwater detonations;

• using Navy observers to shut down sonar operations if marine mammals are seen within designated safety zones;

• using exclusion zones to ensure that explosives are not detonated when animals are detected within a certain distance.

These measures should minimize the potential for injury or death, and significantly reduce the number of marine mammals exposed to levels of sound likely to cause temporary loss of hearing. Additionally, the regulations and authorization include a requirement that the Navy and NOAA’s Fisheries Service meet yearly to discuss new science, Navy research and development, and Navy monitoring results, to determine if modifications to mitigation or monitoring measures are appropriate.

NOAA’s Fisheries Service and the Navy have worked to develop a robust monitoring plan to help better understand how marine mammals respond to various levels of sound, and to assess the effectiveness of mitigation measures. The implementation of this monitoring plan is included as a requirement of the regulations and the authorization. Additionally, the Navy, with input from NOAA’s Fisheries Service, is developing an integrated comprehensive monitoring plan to standardize data collection methods across all of their U.S. range complexes and study areas.

The Navy has been conducting research, development, test and evaluation activities, including the use of active sonar and explosives, in the Gulf of Mexico for more than 60 years. The naval activities provide test and evaluation and in-service support for expeditionary maneuver warfare, operations in extreme environments, mine warfare, maritime operations and coastal operations. A variety of naval assets, including vessels, aircraft and underwater systems support these mission activities for eight primary test operations including air, surface, and subsurface operations, sonar, electromagnetic energy, laser, ordnance and projectile firing.

This regulation, in effect for five years, governs the incidental take of marine mammals during the Navy’s test and evaluation activities, and includes required mitigation and monitoring measures. The letters of authorization, which are required for the Navy to legally conduct their activities, are issued annually, provided the Navy abides by the terms and conditions of the letter, submits the required annual reports, and shows their activities do not result in more numerous effects or more severe harm to marine mammals than were originally analyzed or authorized.