Posted on 10/01/2018 9:21:20 AM PDT by Red Badger
Credit: Chris Ford via Flickr
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Humans did not accelerate the decline of the 'Green Sahara' and may have managed to hold back the onset of the Sahara desert by around 500 years, according to new research led by UCL.
The study by a team of geographers and archaeologists from UCL and King's College London, published in Nature Communications, suggests that early pastoralists in North Africa combined detailed knowledge of the environment with newly domesticated species to deal with the long-term drying trend.
It is thought that early pastoralists in North Africa developed intricate ways to efficiently manage sparse vegetation and relatively dry and low fertility soils.
Dr. Chris Brierley (UCL Geography), lead author, said: "The possibility that humans could have had a stabilising influence on the environment has significant implications. We contest the common narrative that past human-environment interactions must always be one of over-exploitation and degradation.
"The fact that societies practising 'pastoralism' persisted in this region for so long and invested both economically and ideologically in the local landscape, does not support the scenario of over-exploitation. Our study shows that increasing human population and sustainable pastoralism did not accelerate—and may even have delayed—the decline of the 'Green Sahara'."
Around 8,000 years ago, the Sahara wasn't desert, but instead was a vibrant ecosystem that supported hunter-gatherers and fisherfolk. The 'Green Sahara' - the colloquial term for the African Humid Period – was the period in which North Africa became much wetter than it is today thanks to a series of monsoons.
As the Earth's orbit slowly changed, the rain started to reduce, and the vegetation started to die back. Around 5,500 years ago, the ecosystem in the Sahara went into a terminal decline towards the desert we have today.
Pastoralism (nomadic or semi-nomadic cattle-herders) blossomed in the Sahara from around 1000 years before that collapse. Previous studies have put the blame for the collapse of the 'Green Sahara' onto these nomads who have often been marginalised in history, but this latest studies dispels that myth.
The study uses a novel climate-vegetation model to determine whether the end of the African Humid Period occurred earlier than expected. The model keeps track of variables such as vegetation and rainfall, and other processes such as the amount of energy coming from the sun, and the amount of carbon dioxide in the atmosphere.
The model found that the 'Green Sahara' should have collapsed earlier than it did. This suggests that pastoralists lasted longer than expected and the techniques they used helped them to adapt to the environmental changes.
Dr. Brierley added: "Those places where pastoralists last longer are where there are more resources. It's a good adaptation to the climate change taking place at the time. There is now work today looking at what we can learn from nomadic pastoralists, such as selective grazing strategies, which can be applied to sustainable adaption to desertification that we expect from future climate change."
Dr. Katie Manning (King's College London), concluded: "Despite the largely inhospitable conditions of the Sahara today, it is not hard to find evidence of human occupation from the last 11,000 years. Thousands of rock art sites illustrate a lush environment, large-game hunting and livestock herding. The spread of domestic animals across the Sahara occurred at a time of increasing climatic instability, and yet, these pastoralist populations thrived.
"It is likely that strategies used by contemporary traditional herders, such as seasonal movement and selective grazing, were also used by these early pastoralists, helping to maintain an otherwise deteriorating ecosystem."
Explore further: Did humans create the Sahara Desert?
Journal reference: Nature Communications
Provided by: University College London
Changed is the wrong word. It varies slightly over time.
Islam came out of the desert which is the natural habitat of rock-worshiping Arabs; hopefully it will, one day, return to the desert never to be heard of again.
"...an enormous system of cultivation and terracing made great expanses of the Middle East and North Africa fertile and productive. It was the existence of this agricultural infrastructure that permitted the existence of the late classical cities, and conversely, it was the destruction of the same infrastructure which led to their abandonment. But what could have caused such a catastrophe?
" What caused the end of classical civilization? Archaeologists and historians have demonstrated again and again over the past century that the real centre of Graeco-Roman civilization was – and in a sense always had been – in the East. Whoever or whatever destroyed the agriculture and the great cities of the East in the seventh century was also responsible for terminating classical civilization and initiating that relatively dark and unknown epoch we have come to call the Middle Ages.
" In an article entitled “The Decline of North Africa since the Roman Occupation: Climatic or Human?” he provides a detailed outline of the problem. I shall quote him at some length, as what he says is most instructive:
“The Romans were an agricultural people who expanded into their Mediterranean empire from a relatively humid base in Italy. It was natural that they should extend this approach to the natural environment into the African provinces. The Arabs were on the contrary a nomadic people, nurtured in the true desert of Arabia, and totally unused to an agricultural economy.
Their technique was unequal to understanding or managing the highly-developed irrigation works of North Africa bequeathed to them by the Romans, and they had no need for dependence on the agriculture which these works had supported. Their different use of the land does not need to be explained by a change in climate. No military conquest is conducive to the maintenance of civil order nor the administration and technical organization which an intricate irrigation economy requires, especially when the conquerors are nomads. The Arab conquest destroyed the Roman irrigation works, or allowed them to deteriorate, and established in their stead a nomadic pastoral economy over most of North Africa.”
Yet even allowing for the destructiveness of the Arabs, and for their habitual misuse of agricultural land, this in itself does not explain the rapid and complete degradation of the cultivated territories of the Middle East and North Africa. After all, we must suppose that native husbandmen would not lightly have permitted incoming Arab nomads to graze their goats on carefully tilled and planted fields. Furthermore, the Middle East and North Africa had seen numerous invasions before, some of them very violent indeed, but none of them led to the complete destruction of the agriculture of the region. What was so different about the Arab Invasion?
In order to answer this question we need to consider the unique nature of Islam and in particular its application of political and social control through sharia law...."
only if its extermination isn’t an option
Gee, what happened in the 7th Century that caused all this turmoil and destruction?...........If I only had a clue...................
As might be imagined, such oppressive conditions meant that Christians and Jews lived in permanent fear of the predatory attentions of Muslim neighbors, with the result that, over the centuries, the pressure to convert to Islam, or to emigrate from the Muslim-controlled territory, became almost irresistible.
A further exacerbating factor was that under Islamic law Muslims have a right to subsist off the labors and property of the infidel. This is enshrined in the concept of jizya, the tax which all infidels living in the Dar al-Islam must pay to their Muslim masters. But it was not just the Caliph and his emirs who were entitled to live off the infidels. All Muslims, irrespective of position, had this right; and Islamic law thus sanctified the plundering by individual Muslims of the local Christian and Jewish populations.
The long-term consequences of such an outlook are not too difficult to imagine. A general climate of banditry and lawlessness was fostered; and we see, for example, in a very immediate way why immigrant Arab goat-herders in the Middle East and North Africa felt free to allow their flocks to graze on the cultivated lands of their Christian and Jewish neighbors, thus destroying the agricultural viability of these territories and reducing them, within a very short time, to arid semi-desert. One of the most immediate consequences was a dramatic decline in the population. Although precise figures are unavailable, we know that the medieval populations of Anatolia, Syria, Egypt, and North Africa were much smaller than those under the last Byzantine administration. Estimates put the decline at anything from threefold to tenfold; and the result was that by the later Middle Ages large parts of the Middle East and North Africa comprised sparsely populated wasteland, housing economically oppressed and largely impoverished populations. In the fourteenth century, for example, the Islamic scholar Ibn Khaldun, writing in the squalor of what is now Tunisia, marveled at the wealth of a visiting delegation of Italian merchants. And the same attitudes continued to produce the same results well into the nineteenth and even twentieth centuries.
https://newenglishreview.org/Emmet_Scott/The_Fate_of_the_Roman_Cities_of_the_Near_East_and_North_Africa/
and we watch as Western Europe sentences their people to re-learning this same lesson
No kidding. Who could have imagined that?
I’m serious.
Those who fail to learn from history are doomed to repeat it.................
“The desert is an ocean in which no oar is dipped.”
Taking bets on how long it takes Europe’s “migrants” to strip it bare of all vegetation. Probably longer than it’s taking to rape all of its women and destroy all vestiges of civilization.
Thanks Red Badger. It's crap -- there's a recent meme that nomadic herders, who destroy environment over wide areas due to their constant moves after exhausting local food supplies, exacerbate desertification. It's part of the larger luddite scheme to destroy civilization and foster dependency on a small power elite.
Evolution in Your FaceLake Victoria, Africa's largest lake, is home to more than 300 species of cichlids. These fish, which are popular in aquariums, are deep-bodied and have one nostril, rather than the usual two, on each side of the head. Seismic profiles and cores of the lake taken by a team headed by Thomas C. Johnson of the University of Minnesota, reveal that the lake dried up completely about 12,400 years ago. This means that the rate of speciation of cichlid fishes has been extremely rapid: something on average of one new species every 40 years!
by Patrick Huyghe
Omni
[dead link]
“Ice Age Civilizations, James I. Nienhuis”
Sounds interesting. I’ll ask our library to get it. (I’m so funny.)
Whoopsie. Hang up the phone, or post, but don't do both (note to self).
there's a recent meme that nomadic herders, who destroy environment over wide areas due to their constant moves after exhausting local food supplies, exacerbate desertification.
s/b
there's a recent meme that nomadic herders, who destroy environment over wide areas due to their constant moves after exhausting local food supplies, DON'T exacerbate desertification.
The Earth’s rotation changed due to the melting of the glaciers, which led to isostatic rebound of the Earth’s crust. If the melting of the mass of ice in the northern hemisphere caused isostatic rebound in the north, the equator must have cinched up a little, which would actually make the Earth turn a little faster, not slower as indicated here:
In the shadow of the Moon
New Scientist | 30 January 1999 | editors
Posted on 08/31/2004 8:42:25 AM PDT by SunkenCiv
http://www.freerepublic.com/focus/chat/1203912/posts
Thanks marktwain for that link. Regarding Milankovitch cycles:
Variations in the Earth's eccentricity, axial tilt, and precession comprise the three dominant cycles, collectively known as the Milankovitch Cycles for Milutin Milankovitch, the Serbian astronomer and mathematician who is generally credited with calculating their magnitude. [Milankovitch Cycles and Glaciation]
The tidal transfer of momentum pushes the Earth away from the Sun (from both sides), in the same way that the Earth pushes away the Moon (and prior to its loss of rotational energy, the way the Moon used to push away the Earth) which means that, over time, the Earth has been moving away from the Sun, and continues to do so. This has had a longterm impact on the length of the sidereal year and the angular velocity of the Earth (the farther we get away from the Sun, the slower it goes. Don't argue with me about it, argue with Kepler). IOW, the orbit of the Earth isn't fixed and immutable, even without taking catastrophes into account.
For axial motion fans, look up Chandler Wobble.
When the Days Were Shorter [alas, a dead link]
Alaska Science Forum (Article #742) | November 11, 1985 | Larry Gedney
Posted on 10/04/2004 10:31:59 AM PDT by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1234919/posts
Earth’s days used to be just 18 hours long, but the Moon changed that
BGR.com | 6 Jun 2018 | Mike Wehner
Posted on 06/07/2018 3:49:48 PM PDT by DUMBGRUNT
http://www.freerepublic.com/focus/chat/3661396/posts?page=13#13
+1 for not saying Earth rotates around the Sun — despite its rotations...
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