Monday, February 14, 2011

How did they survive? New research shows Jordanian city survived climate change disaster 4,200 years ago

4,200 years ago Tall el-Hammam survived a climate change disaster that
decimated civilizations throughout the Middle East.
A map of Tall el-Hammam, archaeologists believe that an abundence of
water resources helped this city survive the arid conditions that hit the
Middle East 4,200 years ago.
Evidence suggests that, as the climate grew arid, there was an
increasing number of nomadic groups in the Levant.  This gate at
Tall el-Hammam was blocked off about 4,200 years ago,
likely in an attempt to keep them out of the city.

(4) Shows the blockage, (1) and (2) show the passageway walls of the gateway
(6) shows the walking surface as it was 5,000 years ago. (3) shows the
surface as it was 4,500 years ago and (5) shows fill that was put in
to level the gateway with the ground 4,500 years ago.
It's estimated that nearly 1,000 dolmens existed at Tall el-Hammam.
Archaeologists believe that they were used in ancestor worship.
NOTE - All photos and maps courtesy Tall el-Hammam Excavation Project

About 4,200 years ago a series of disasters struck cities and civilizations throughout the Middle East.
In Egypt the central government collapsed. The same state that had built the great pyramids, and kept pharaoh as the supreme authority, could no longer keep the country united. This ushered in an era of powerful provincial leaders (known as nomarchs) and rival claimants to the Egyptian throne.
A similar scenario happened in Mesopotamia where the Akkadian Empire, an entity whose power stretched from the Persian Gulf to the Mediterranean, also went under. This led to local rulers stepping in and taking up power. 
There is also evidence of social upheaval in the Levant. The city of Khirbet ez-Zeiraqoun in northern Jordan, whose inhabitants burrowed out hundreds of meters of water tunnels into the ground, was abandoned.
Climate change is believed to be a major reason for this upheaval. Research in the Middle East suggests that the environment became increasingly arid – making it difficult to support the intensive farming that is required to feed large cities.
“Paleoclimactic data from numerous sites, document changes in the Mediterranean westerlies and monsoon rainfall during this event with precipitation reductions of up to 30%, that diminished agricultural production from the Aegean to the Indus,” wrote scientists Harvey Weiss and Raymond Bradley in a paper they published.
“What that climate change is a result of is a mystery,” said Professor Steven Collins, of Trinity Southwest University. “There are even folks speculating on some sort of cosmic impact event like an asteroid strike at some point on the globe that created some sort of climatological disaster for the whole planet, not just for the Middle East.”
Together with Khalil Hamdan, of Jordan’s Department of Antiquities, Collins leads archaeological work at the Jordanian city of Tall el-Hammam. Located in the southern Jordan Valley, new research at this 36 hectare city shows that, remarkably, it continued to operate during this climate shift. “It was not only around it was thriving,” Collins said.  
An ancient metropolis
Archaeological work shows that people were living at Tall el-Hammam at least as far back as 6,000 years ago.
By the time the climate disaster hit, nearly 4,200 years ago, the city supported a population of between 15,000 to 25,000 people living in or nearby.
The team believes that it was the centre of a small kingdom ruled by a king. The city certainly had its share of amenities. A 100 meter by 100 meter raised platform served as the main hub of the city, containing temples and administrative buildings.
The city was protected by a massive fortification system with walls that Collins said were “about six meters thick and would have been about three times that high.” These fortifications had somewhere between 15 and 20 gates, giving outsiders access to the settlement.  
Domestic residences in the city were modest. Built of mud brick, they had stone foundations and walls that were half a meter thick. Archaeological work suggests that these houses were reused and modified over a vast amount of time. One residence the team found was used from between 4,600 and 3,600 years ago, with modifications being made occasionally.
One of the most enigmatic features of the city was its dolmen field. In ancient times the people of Tall el-Hammam built nearly 1,000 of these stone monuments. “They go up into the hills surrounding the east and south of the city state,” said Collins.
Many of the dolmens have either been destroyed or looted but the team has found a few intact examples. From the excavation of them “we pretty much concluded that they’re not primary burials, and they’re probably not even secondary burials,” said Collins. Rather “they seem to be memorial monuments related to some sort of ancestor worship.”
What may have taken place is that on certain days people would have opened the grave of an ancestor, taken a bone out and had it “ritually placed (near the dolmen) with some sort of small offering like a juglet of wine, or a juglet of oil, or a bowl of some sort of offering.”
Climate change survivor
All together the picture the evidence paints is that Tall el-Hammam was a thriving place when it entered the climate catastrophe. “It’s very dramatic and it’s obviously a very long enduring powerful city state,” said Collins.
When the climate changed, about 4,200 years ago, many of the cities and civilizations in the Middle East were wiped out. The increased aridity made it hard for them to grow crops and keep up an urban way of life.
“As a result the large majority of the cities in the Levant, particularly the southern Levant, completely went out of business,” said Collins.
But the people did not go away. As agriculture became untenable in many areas people became nomads, turning to pastoralism as a way to survive. It was a “period of extreme social upheaval in the region, there would have been a lot of nomads and semi-nomads ranging about, threatening cities, especially cities that were wealthy and thriving.”
Among those few cities still surviving was Tall el-Hammam. The team’s research reveals that the defences of the city were bolstered – with many of the city’s gates being blocked off, probably in an effort to keep those nomads out.
The effort seems to have helped, at least on some level. The city continued to be occupied throughout this period of climate collapse. Collins said that the team needs to do more excavation to get a complete sense of how the city was affected but so far the findings show that the houses were occupied “pretty much throughout (the) interruption.”
All in all “my gut feeling now is that the city footprint – residences, temples, administrative buildings, palaces – didn’t change appreciably or maybe even at all.”
Why did it survive?
This discovery raises an important question – why did it survive? Blocking off the entrances alone would not have done it. While that would have helped prevent nomads from getting in, it would not have helped the residents grow food.
Collins believes that access to water is the reason why the city survived. Unlike many areas in the Middle East, the people at Tall el-Hammam had it in abundance and coming from multiple sources.
“It really boils down to the water resources,” said Collins.
“You have the Jordan river which, even in the worst case scenario, never would have dried up.” Also “you have two perennial rivers one (on) the north, one on the south, that would have continued to flow most of the time, even in a very dry climate regime.” In addition a number of springs, fed by groundwater, also would have brought in water.
One other factor is the temperature in the southern Jordan Valley. Not only did people have access to a good amount of water but they also had the ability to grow crops year-round.
“With the right water resources you can grow several crops a year,” said Collins. “It might be snowing and freezing up in Amman or up in Jerusalem but down in the valley it will be 60, 70 or 80 degree (Fahrenheit).”
So what lesson can we take away from this? Like people 4,200 years ago our civilization is facing a period of climate change (although this time induced by humans). Is there something that the experience of this ancient city can teach us?
“The lesson is to be smart about the utilization of water resources,” said Collins. “People need to do what Tall el-Hammam did and very carefully manage their water resources so they can survive.”


  1. Whatever the cause 4200 years ago, it could not have been man induced. There were not enough of us around to manage it. Keep archaeology out of the global warming debate. The global warming 'scientists' are now a laughing stock for fudging 'evidence' and outright lying to the public. Keep their discomfort in their own discipline and out of archaeology if you want to be taken seriously as a science and not a political tool.

  2. Agree completely,anonymous #1.Science and politics do not mix and has been proven.Those with an agenda are politicians and those with an open mind are scientists.

  3. The previous comments are ignorant at best and complete bullshit at worst. Read the article instead of looking up the term global warming on google and posting your republican bullshit propaganda on every article with the term in it. By the way leave the science to real scientists and you can keep the opinions of your oil corporation "scientists" where you keep your heads, up in your collective asses. Jerk-offs.

  4. Hello all, please let's keep the comments civil. Two points:

    - The science is strong that the global warming we're experiencing today is largely (or entirely) human made.

    -It's not known what caused the climate shift that occurred 4,200 years ago however it probably was a natural phenomenon of some sort.

  5. Anonymous 1 and 2 fail to consider the possibility that perhaps there was enough human activity to effect the environment at the time-man-made fires, the clearing of vast amounts of land in converting from hunter-gatherer modes of production to agriculture and agro-pastoralism.
    Of course, if you don't care about facts or science but would rather be contrarian for its own sake, so be it. In that case, whatever conspiracy theory you prefer will suffice and rational thought and scientific process will never be sufficient for you. Reality does have a well-known liberal bias, as Stephen Colbert has pointed out.

  6. The Bible account of the time of Abraham reveals a great shift that affected all of Mesopotamia. The Bible reveals that drought crippled a large area of the middle east while Egypt was humid and lush. After this, Egypt became arid.
    This is all post-flood climate change as the earth was undergoing changes.

  7. The article mentions a possible comet strike that might have caused the weather changes. I do think the fact that other planets are experiencing climate change right now definitely points to something other than humans for climate change. Everyone should pay more attention to science right now to get answers.

  8. The event 4200 years ago has been linked with a cool, arid episode of a type that has recurred every 1-2 thousand years throughout the past 10,000 years and probably longer (often known as "Bond events" after their discoverer). It looks as if such episodes are associated with changes in the North Atlantic circulation, although the drivers and mechanisms associated with such events are poorly understood. There's no reason to think that these are anything other than entirely natural (i.e. non-human induced) phenomena, that are manifestations of the internal variability of the Earth's climate system.

    So we can keep the global warming fury elsewhere. Archaeology has a lot to teach us about how people have responded to past abrupt and severe changes in climate, so is relevant to current debates in that respect, but we're looking at very different climatic mechanisms and processes here. Having said that, past episodes of climate change can tell us a lot about how elements of the climate system respond to external forcings, and can help us constrain things like climate sensitivity (i.e. how much warming is likely to result from given changes in greenhouse gas concentrations). However, this is more applicable to more distant periods than to the 4200 yr event.

  9. Is it a coincidence that the "climate change disaster" took place about the same time that the Lord destroyed Sodom and Gomorrah? Genesis 13:10, ...Lot...beheld all the plain of Jordan, that it was well watered every where, before the Lord destroyed Sodom and Gomorrah... .
    A cosmic impact event would fit the situation very well, don't you think?

  10. Thank you for your comment AB.

    Two points:

    -The idea has been raised that Tall el-Hammam may be Sodom. If you go to the project's webpage and scroll down you'll see a discussion about it.

    -I should caution, linking biblical events to archaeological events is a great, but interesting, challenge.

    The story of Sodom and Gomorrah for instance - does it refer to an actual historical place and event? Or is it a cautionary tale meant to tell an audience how not to behave?

    Also if it is a historical event which one do we link it to? The event 4,200 years ago would be a poor candidate. In this instance cities throughout the Middle East collapsed but Tall el-Hammam actually survived.

    The point where the city is destroyed ca. 3,600 years ago would be a more likely choice.

  11. The famine of Genesis 41:56,57 corresponds to the destruction of Tall el-Hammam ca. 3,600 years ago. "The famine was all over the face of the earth... And all the countries came into Egypt to Joseph for to buy corn; because that the famine was so sore in all the lands". The story of Sodom and Gomorrah corresponds to the climate change about 4,200 years ago and you are excavating one of the few cities in the region that survived. Tall el-Hammam is not Sodom.

  12. And 3600 (well actually 3450 but at this distance it may be hard to tell the difference) years ago would be when Moses was bringing the Israelites through what is now Jordan and destroyed the kings there. (Though according to the Numbers 21 they had also been busy destroying each other.)

  13. Trying to link archaeology to Biblical stories is a tenuous task at the very least.
    For what its worth we are in a natural warming period, it's called an interglacial. So-called Global Warming is a political theory, not a scientific theory.

  14. Hello all, a reader named "Cecile" asked me to put this comment up.


    As a recently retired teacher and *new* student of Horticulture, I've been learning some interesting things at my local community college. They supplement forty years of growing various veggies and herbs in small backyard plots or containers. I began composting in 2004.

    This statement got me thinking of several things:

    RE: Climate change is believed to be a major reason for this upheaval. Research in the Middle East suggests that the environment became increasingly arid - making it difficult to support the intensive farming that is required to feed large cities.

    Desertification--a process whereby the organic plant materials in the soil are removed through wind, erosion, and chemical alteration of the pH or acidic balance--has occurred all over the Middle East and the Sahara. I believe this has been man-made. Tilling the soil and using "intensive farming" both create situations where the soil food web of microorganisms is dried out, and the organic matter blows away or is washed away with erosion-force watering or rain storms.

    By cutting down trees, wind patterns and cloud formations change. Yearly organic matter is needed in the soil to maintain the microorganisms, and when that plant material isn't returned to the soil, the microorganisms' numbers decrease and fertility decreases,. With intensive farming, this resuls in the addition of more amendments that change the pH even more, causing more microorganism death.

    Organic matter in the soil is a moisture retainer. Without it, water either moves quickly through the mineral/ sand components of soil or sits on top of compacted clay soils. Also, without organic matter, no earthworms can live. They too are vital parts of the soil food web that provides nutrition to plants.

    The second thought:

    It rains from under the earth and not from the sky.
    ~ Masanobu Fukuoka

    Fukuoka was an earnest soil scientist and horticulturalist who studied for decades the results of such practices as tilling the soil and adding of amendments. He knew the rain --both quality and quantity--was determined by the ground, not the sky. Where I have lived for the past forty years, I've watched how trees were cut down to provide growing space for berries, how fields are now tilled and left bare because land is no longer farmed by the owner but by lessees who stay for only part of a year. And how rainfall patterns have changed --both the amount and how it rains are altered.

    I venture to say the upheavals in the Middle East--the change from large, lush forests and rich, vibrant soil to desert--was caused by man-made climate change: first the forests were cut, then soil was tilled--allowing it to not follow the natural cycle of yearly additions of plant material, then artificial irrigation was practiced, and as the rain responded to more wind, less moisture in the soil, and a dying soil food web, the desertification began. Now we have the desert not the Fertile Crescent.

    Civilizations have disappeared because of lack of soil considerations. Tilling is one dangerous action; its practice guarantees the death of natural soil fertility. In the U.S., as more and more additives and water are needed to produce the same crop, we're looking at this "death" of our soil. Be prepared.
    B.A. Anthropology

    "All the fertile areas of this planet have
    at least once passed through the bodies
    of earthworms."
    -- Charles Darwin, "

  15. Fatez says:
    Anonymous number 3 starts in with "the only smart scientist know that global warming is a fact" and other views are 1: either ignorant or 2: funded by the oil industry. Another poster describes the Bond event of 4.2 K ago. This bond event is a cooling according to most interpretations and in fact cooling almost always leads to desertification and warming leads to a more humid climate. Instead of airing your comments Anonymous 3 and displaying your ignorance on science, please keep your bigotry to yourself...

  16. LOL,

    To all the scientific know-it-alls. Science or the scientific consensus as it is practiced today may not lead to truth.

    I remember how in grad school our physics dept was being downsized to make way for the "new" study of climate change. These professors where more concerned about finding reasons for their models NOT predicting global warming than investigating the evidence.

    If I run 3 trails and 2 of them predict the result I wanted and 1 didn't, guess what was done about the abnormal result?

  17. Biblical believers should keep to religious websites. They can debate with conservative rabbis, ayatollahs, living Buddhas, and the like. When they come to scientific sites, they often sound like their minds are still locked in the Bronze Age.

  18. Hmmmm-- I view the previous post as not only harsh, but narrow minded as well. Given the area we're looking at, biblical writings need to be considered for possible context. The actual linking, as been stated, is difficult but interesting as well. If one truly objects to this type of linking, may I suggest avoiding this geographical area.
    As to causes for climate change, speculate as you will, but methinks no climatological experts are posting here. Opinions are like_________(fill in the blank), everyone has one. Happy Easter--Peace and happiness to all.

  19. The dolmens and other megaliths (pyramids, cromlechs, and others) were built for defense. Read more


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