Published on April 4th, 2017 | by James Ayre0
Middle East Rainfall Fell To 1/5 Modern Levels 120,000 Years Ago (& 10,000 Years Ago As Well) — Implications For Anthropogenic Climate Change
April 4th, 2017 by James Ayre
Rainfall levels in the Middle East fell to nearly one-fifth of modern levels around 120,000 years ago, and again around 10,000 years ago, according to new research. To put that in different terms, the Middle East at those times experienced a degree of drought that hasn’t been seen in modern or historical times (in the region).
Image of the Dead Sea by David Shankbone/Wikimedia Commons via Columbia University
The research is notable since the region is currently drying out again, in concert with rising temperatures. The new research thus represents a cautionary tale about where things are headed in the region. (Where will the region’s substantial population head as a result of the coming changes?)
“All the observations show this region is one of those most affected by modern climate change, and it’s predicted to get dryer. What we showed is that even under natural conditions, it can become much drier than predicted by any of our models,” commented lead author Yael Kiro, a geochemist at Columbia University’s Lamont-Doherty Earth Observatory.
It’s an interesting point to make, as most climate models are likely greatly underestimating the speed and extent of the changes that are coming — even just a look at the relatively recent past of the last 50,000 years makes it clear that current climate models are unrealistically conservative about such things.
The press release from Columbia University provides more: “Nearly 1,000 feet below the bed of the Dead Sea, scientists have found evidence that during past warm periods, the Mideast has suffered drought on scales never recorded by humans — a possible warning for current times. Thick layers of crystalline salt show that rainfall plummeted to as little as a fifth of modern levels some 120,000 years ago, and again about 10,000 years ago. Today, the region is drying again as climate warms, and scientists say it will get worse. The new findings may cause them to rethink how much worse, in this already thirsty and volatile part of the world. …
“The landlocked Dead Sea, straddling Israel, Jordan and Palestinian lands, is earth’s lowest spot on land. Its current shoreline lies about 1,300 feet below sea level, and its floor extends down another 900 feet. Fed mainly by the Jordan River drainage, which extends also into Syria and Lebanon, it is a dead end for water, and so is extremely salty; its Biblical name in Hebrew is Ym ha-Melah, the sea of salt. In recent years, its level has dropped about 4 feet a year. But hot, dry weather is not the main cause yet; rather, booming populations in the region need more water than ever, and people are sucking so much from the watershed, very little reaches the Dead Sea, where evaporation is outweighing input.”
A short note should be made here to remind those reading this that the 1998–2012 drought in Syria, along with the country’s fast-declining oil industry/extraction, played a major role in setting off the civil war that the country is now experiencing. (While the resource problems certainly played a major part in setting things off, there’s no doubt that at this point foreign money and mercenaries are keeping the problems aflame.)
The press release continues: “In 2010, scientists from a half-dozen nations drilled 1,500 feet into the deepest part of the seabed, bringing up a cross section of deposits recording 200,000 years of regional climate history — the longest such archive in the Mideast. … The cores revealed alternating layers of mud washed in with runoff during wet times, and crystallized salt, precipitated out during dry times when the water receded. This instantly made it clear that the region has suffered epic dry periods, but the core was not analyzed in great detail until now.
“The new study shows that the salt accumulated rapidly, an estimated half-inch per year in many cases. The researchers spotted two striking periods. About halfway down they found salty layers some 300 feet thick, indicating a long-term drop below the sea’s current level. This came in a period between ice ages, 115,000 to 130,000 years ago, when variations in Earth’s orbit brought temperatures about 4 degrees hotter those of the 20th century, equivalent to what is projected for the end of the 21st century. The lake refilled when glaciers readvanced in sub-polar regions and the Mideast climate cooled and became moister. The cores show a similar drop in lake level just 6,000 to 10,000 years ago, following the most recent ice age, when temperatures were probably a bit cooler than now.
“The chemistry of tiny fluid bubbles within the salt allowed the researchers to extrapolate rainfall and runoff patterns of these periods. They calculated that runoff to the Dead Sea generally declined 50% to 70% compared to today, dwarfing current projections for this century. In the most extreme periods, it went down 80%, and this lasted for decades to centuries at a time.”
Much of these declines was no doubt linked to major shifts in atmospheric flow and rainfall patterns, as well as to higher temperatures and increased rates of evaporation.
So, where does all of this leave us? With intensive human exploitation of local water resources factored in, it seems likely that water scarcity will be the driver of a large population shift out of the region over the coming decades and century.
“The Dead Sea is wasting away today because humans are using up all its fresh water sources,” commented Steven Goldstein, a geochemist at Lamont-Doherty and coauthor of the paper who helped oversee the 2010 drilling. “Our study shows that in the past, without any human intervention, the fresh water nearly stopped flowing. This means that if it keeps getting hotter now, it could stop running again. This time, it would affect millions of people.”
So, the research is yet another warning of where things are going, and of the slow motion train-wreck that we have already now begun to experience. Which reminds me of when I was told by a researcher local to the New Orleans area about the extreme flooding problems that would accompany a direct hit by a hurricane or tropical storm … back in 1995 or so.
The new research is detailed in a paper published in the journal Earth and Planetary Science Letters.
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