Sediments pulled up from a drilling project in the Dead Sea suggest that the salty lake completely disappeared about 120,000 years ago, a finding that violates assumptions long held by scientists. The results, reported at a meeting of the American Geophysical Union in San Francisco on 5 December, raise questions about how the warming climate will affect the endangered sea, where water levels have been dropping rapidly in the past few decades.
The US $2.6 million international Dead Sea Deep Drilling Project bored a series of holes into the lake from November 2010 to March 2011 to study the climate and earthquake history in the region. Last month, the team finished opening up the sediment cores and discovered a layer of rounded pebbles 230 meters below the surface of the seafloor. The pebble layer represents an ancient beach that filled the lowest level of the basin as the lake was drying up completely or nearly so, the researchers propose. “There’s nothing else like it in the core,” says Steven Goldstein, a researcher at the Lamont-Doherty Earth Observatory in New York and a leader of the project. The Dead Sea work was funded by the International Continental Scientific Drilling Program and by Israel, Germany, Japan, Norway, Switzerland and the United States.
Experiments in the past using water from the Dead Sea had suggested that the lake could not disappear totally because the loss of water would concentrate salt within the lake, inhibiting further evaporation. But the new findings call that assumption into question. Climate forecasts suggest that the region will grow warmer and drier in the future, says Emi Ito, a lake researcher at the University of Minnesota and a principal investigator on the drilling project.
The lake level has been dropping precipitously recently because Israel and Jordan divert water that previously flowed into the Dead Sea. In the past 14 years, the lake surface has lowered by 14 metres and now stands at 425 metres below sea level. Israel and Jordan are considering a controversial proposal to refill the lake by constructing a canal from the Red Sea into the Dead Sea.
photo: Dead Sea Drilling Barge (credit: OSG-GFZ, ICDP)