April 12, 2012
Was The Dead Sea Once, In Fact, Dead?
As towns and villages continue to use its run-off water, levels of the Dead Sea have continually been dropping for the past few years. However, according to new research, this may not be the only time the Dead Sea has shrunk, even without our help. In fact, it may have dried up almost entirely more than 100,000 years ago.
Such a finding is troublesome for researcher Steven Goldstein, professor at the Lamont-Doherty Earth Observatory at Columbia University, reports Stephanie Pappas for LiveScience. If this large, vast body of water was able to dry up without any human pressures, then a damaging one-two punch from mankind and their climate change may have dire effects on the Sea.Speaking at the American Geophysical Union (AGU) in late 2011, Goldstein said, “Without human intervention during the last interglacial, the run-off declined or stopped.”
Speaking of climate change, the area surrounding the Dead Sea is expected to become dry and arid, multiplying the strain placed on water sources. In fact, there are already some indicators this is already happening, In 1930, the lake´s surface stood at 1,280 feet below sea level. By 2008, this level had dropped to 1,381 feet below sea level as humans used up water faster than it could be replaced.
In order to study the lake´s past, Goldstein and his colleagues drilled below the sea bed (both in 2010 and 2011 ) to pull up long columns of sediment 1,300 feet long. This research was done as a part of the Dead Sea Deep Drill Core Project. These columns provide more than 200,000 years worth of Deep Sea sediment.
The columns offer proof of nearly every season in this 200,000 year time span. As summer heat causes evaporations, white layers of aragonite are formed. When floods and sandstorms deposit silt into the lake, dark layers are formed.
Goldsmith and his team could see some of these formations in rocks on the Sea´s shore, proof the lake had previously fluctuated in size as it filled the entire Jordan Rift Valley during the last ice age. With access to an even larger treasure trove of historical information, the team now has proof the sea may have almost completely dried up around 120,000 years ago. At this point in the core, the team found a layer of round beach pebbles on top of a layer of salt nearly 150 feet deep.
The team says this means the lake wasn´t quite completely dry, as this sample wasn´t taken from the very bottom of the Sea.
According to Zvi Ben-Avraham, chief scientist on the project and a researcher at Tel-Aviv University, this ancient dry spell was caused by climate changes. Today, the lake is not only in danger of the same threat, but also human demand and taxation.
“What we see here happening in the Middle East is something that mimics a severe dry period, but this is not climate-enforced, this is a man-made phenomenon,” said Ben-Avraham. He said irrigation captures most of the water before it ever reaches the Dead Sea.
While researchers aren´t yet sure how long it took the lake to nearly go dry, they are changing the way they´ve thought about the Sea.
“The global warming scenario is definitely predicting that the area is going to be even drier and warmer than it is today,” said Emi Ito, a study researcher from the University of Minnesota.
Ito estimates the sea may not completely dry out again, but stabilize around 328 and 492 feet below sea level.