Friday, April 14, 2017

Did Lack of Private Property Rights Cause the Sahara Desert to Form?

The below essay by David Wright, Managing Partner, Trilateral Research & Consulting, does not discuss property rights but merely considers the fact that the Sahara desert was lush green at one time and that it was likely that humans that allowed domesticated livestock feeding on the greens that caused the desert.

Of course, any economist who understands the nature of private property will tell you that it would be very unlikely for a private property owner to allow his property to turn into a desert. It doesn't happen on grazing land today on private property in the United States. 

The "burning" of green lands makes much more sense when the property isn't owned and a herder can just move his herd onto a new, non-private property owned, piece of land.

It should also be noted that Wright at the end of the essay reveals something thinking in line with that of a central planner. He does not recognize that private property solves the "burning" problem. when he writes
In the meantime, we must balance economic development against environmental stewardship. 
But what is this "we" all about. If a rancher is limited to grazing his livestock on his land, he is not going to let his land turn into desert. There is no "environmental stewardship" needed by anyone but the rancher. Private property and the profit incentive eliminates the problem.


How human error could have created the Sahara desert
By David Wright

Once upon a time, the Sahara was green. There were vast lakes. Hippos and giraffe lived there, and large human populations of fishers foraged for food alongside the lakeshores.

The “African Humid Period” or “Green Sahara” was a time between 11,000 and 4,000 years ago when significantly more rain fell across the northern two-thirds of Africa than it does today.
The vegetation of the Sahara was highly diverse and included species commonly found on the margins of today’s rainforests along with desert-adapted plants. It was a highly productive and predictable ecosystem in which hunter-gatherers appear to have flourished.

These conditions stand in marked contrast to the current climate of northern Africa. Today, the Sahara is the largest hot desert in the world. It lies in the subtropical latitudes dominated by high-pressure ridges, where the atmospheric pressure at the Earth’s surface is greater than the surrounding environment. These ridges inhibit the flow of moist air inland.

How the Sahara became a desert

The stark difference between 10,000 years ago and now largely exists due to changing orbital conditions of the earth – the wobble of the earth on its axis and within its orbit relative to the sun.
But this period ended erratically. In some areas of northern Africa, the transition from wet to dry conditions occurred slowly; in others it seems to have happened abruptly. This pattern does not conform to expectations of changing orbital conditions, since such changes are slow and linear.
The most commonly accepted theory about this shift holds that devegetation of the landscape meant that more light reflected off the ground surface (a process known as albedo), helping to create the high-pressure ridge that dominates today’s Sahara.

But what caused the initial devegetation? That’s uncertain, in part because the area involved with studying the effects is so vast. But my recent paper presents evidence that areas where the Sahara dried out quickly happen to be the same areas where domesticated animals first appeared. At this time, where there is evidence to show it, we can see that the vegetation changes from grasslands into scrublands.

Scrub vegetation dominates the modern Saharan and Mediterranean ecosystems today and has significantly more albedo effects than grasslands.

If my hypothesis is correct, the initial agents of change were humans, who initiated a process that cascaded across the landscape until the region crossed an ecological threshold. This worked in tandem with orbital changes, which pushed ecosystems to the brink.

Historical precedent

There’s a problem with testing my hypothesis: datasets are scarce. Combined ecological and archaeological research across northern Africa is rarely undertaken.

But well-tested comparisons abound in prehistoric and historic records from across the world. Early Neolithic farmers of northern EuropeChina and southwestern Asia are documented as significantly deforesting their environments.

In the case of East Asia, nomadic herders are believed to have intensively grazed the landscape 6,000 years ago to the point of reducing evapo-transpiration – the process which allows clouds to form – from the grasslands, which weakened monsoon rainfall.

Their burning and land-clearance practices were so unprecedented that they triggered significant alterations to the relationship between the land and the atmosphere that were measurable within hundreds of years of their introduction.

Similar dynamics occurred when domesticated animals were introduced to New Zealand and North America upon initial settlement by Europeans in the 1800s – only in these instances they were documented and quantified by historical ecologists.

Ecology of fear

Landscape burning has been occurring for millions of years. Old World landscapes have hosted humans for more than a million years and wild grazing animals for more than 20 million years. Orbitally induced changes in the climate are as old as the earth’s climate systems themselves.
So what made the difference in the Sahara? A theory called the “ecology of fear” may contribute something to this discussion. Ecologists recognise that the behaviour of predatory animals toward their prey has a significant impact on landscape processes. For example, deer will avoid spending significant time in open landscapes because it makes them easy targets for predators (including humans).

If you remove the threat of predation, the prey behave differently. In Yellowstone National Park, the absence of predators is argued to have changed grazers’ habits. Prey felt more comfortable grazing alongside the exposed riverbanks, which increased the erosion in those areas. The re-introduction of wolves into the ecosystem completely shifted this dynamic and forests regenerated within several years. By altering the “fear-based ecology”, significant changes in landscape processes are known to follow.

The introduction of livestock to the Sahara may have had a similar effect. Landscape burning has a deep history in the few places in which it has been tested in the Sahara. But the primary difference between pre-Neolithic and post-Neolithic burning is that the ecology of fear was altered.
Most grazing animals will avoid landscapes that have been burned, not only because the food resources there are relatively low, but also because of exposure to predators. Scorched landscapes present high risks and low rewards.

But with humans guiding them, domesticated animals are not subject to the same dynamics between predator and prey. They can be led into recently burned areas where the grasses will be preferentially selected to eat and the shrubs will be left alone. Over the succeeding period of landscape regeneration, the less palatable scrubland will grow faster than succulent grasslands – and, thus, the landscape has crossed a threshold.

It can be argued that early Saharan pastoralists changed the ecology of fear in the area, which in turn enhanced scrubland at the expense of grasslands in some places, which in turn enhanced albedo and dust production and accelerated the termination of the African Humid Period.

I tested this hypothesis by correlating the occurrences and effects of early livestock introduction across the region, but more detailed paleoecological research is needed. If proven, the theory would explain the patchy nature of the transition from wet to dry conditions across northern Africa.

Lessons for today

Although more work remains, the potential of humans to profoundly alter ecosystems should send a powerful message to modern societies.

More than 35% of the world’s population lives in dryland ecosystems, and these landscapes must be carefully managed if they are to sustain human life. The end of the African Humid Period is a lesson for modern societies living on drylands: if you strip the vegetation, you alter the land-atmosphere dynamics, and rainfall is likely to diminish.

This is precisely what the historic records of rainfall and vegetation in the south-western desert of the United States demonstrates, though the precise causes remain speculative.

In the meantime, we must balance economic development against environmental stewardship. 

Historical ecology teaches us that when an ecological threshold is crossed, we cannot go back. There are no second chances, so the long-term viability of 35% of humanity rests on maintaining the landscapes where they live. Otherwise we may be creating more Sahara Deserts, all around the world.

The above essay originally appeared at the World Economic Forum.


  1. Amazing that someone writing for the WEF attributes the dryness of the area to "changing orbital conditions of the earth – the wobble of the earth on its axis and within its orbit relative to the sun" and not [drum roll] man-made carbon emissions (or Charles Murray).

  2. Indeed that's how it goes, but that fails to stop the desertification according to this talk:

    If livestock is used in a way that mimics natural herds the desertification can be stopped and even reversed.

  3. Just because the change of the wobble is slow doesn't mean this would have a slow effect on climate, nor do climate changes effect everywhere to an equal extent.

  4. The author also displays a Sahara Desert of his own mind. There certainly is something to be concerned of with the over farming of domesticated livestock, particularly cattle, and the monocultured crops that are entwined with their feeding but also allowing public lands to be used by government paying BIG business operatives is the modern example of BAD resource management all around. This protein diet obsession is also more myth than good health sense.

    The story is also sketchy to assume this 'mass' animal raising in long ago periods of limited population and limited pop growth could be the possible long term effect of producing deserts. It is more likely the climate change that changed the landscape from more tropical to ice-aged based; and of which we geographic timeframe wise or slowly coming out of.

    Also, seems to call more for global warming CO2 promotion rather than fear, since all lush growing periods historically have shown to be multiple times greater in CO2 density than this BS anthropomorphic fear based statism as the cause for coming off historic lows. Under 150 ppm CO2 all plant life, including ALL life, would cease to exist.


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