Has human activity caused the spread of deserts in the Middle East and worldwide, and can human intervention reverse it?

This wide reaching question not only looks into the past, but into the future. To answer this question about desertification well, let us consider the following sub-questions…

Has human activity caused massive land degradation and deforestation resulting in a change to drier climates?

That important question cannot be conclusively answered, though all available evidence indicates that the rapid spread of civilization has wreaked havoc on the semi-arid ecosystems of the Middle East and dramatically accelerated the spreading of deserts in Northern Africa, Arabia, and Central Asia already between 5000 and 10000 years ago, as eloquently reviewed by Ruddiman. Growing resource needs of early civilizations, mainly for firewood, construction, shipbuilding’ and the growing need for agricultural products, must have induced massive deforestation and land clearing early on, resulting in massive erosion and soil degradation especially in the sensitive semi-arid areas (Fig. 12).

Similarly, Lawton et al (Lawton RO, Nair US, Pielke Sr RA, Welch RM). Climatic impact of tropical lowland deforestation on nearby montane cloud forests. (Science. 2001 Oct 19; (5542):584-7) have clearly demonstrated and modelled the impact lowland deforestation had on cloud formation and precipitation in Central America (Fig. 13). The same mechanisms acting on Mediterranean drylands are schematically summarized in Fig. 14.

Have other semi-arid areas around the world experienced similar fates?

All areas with emerging civilizations worldwide experienced massive land use change, deforestation and land degradation more than 2000 years ago (Fig. 15). The Southern Arabian Peninsula, Central Asia, Central America, Peru, and Northern Africa were all densely populated by emerging civilizations, and their agricultural activities very likely caused irreversible land degradation and desertification increasing the World’s desert areas by at least 100%, if above feedback mechanisms between climate and vegetation are being taken into account.

Evidence from Southern Spain indicates that early towns along Spain’s southwestern coast lost their basis of existence in parallel with large scale vegetation degradation nearby.

Similarly the work of Beresford-Jones and colleagues describes the disappearing of the Nazca culture in Western Peru and is correlation with overexploitation of Prosopis populations along the dry valleys, and resulting soil erosion and desertification.

The most massive land degradation only poorly described apparently affected the steppes of central Asia, from Turkey till western China, Afghanistan and India in the East. Those areas are crossed by major river systems, and majestic inland seas, offering an excellent resource base for large numbers of nomadic people and highly developed civilizations such as the Persian Empire. However, construction and maintenance of towns and infrastructure likely resulted in rapid deforestation of the areas semi-arid mountain slopes leading to massive desertification, disruption of the hydrological cycles and loss of biological productivity and ecosystem resilience.

Were Ottoman Palestine and the Mediterranean semi-arid ecosystems deserts in the 19^th century?

Absolutely. Israel is one of the view dryland countries that has been able to deliver convincing experimental proof that the local ecosystem was profoundly and irreversibly degraded at the beginning of the twentieth century when civilization, industrialization, modern science and advanced agriculture started entering the area after the demise of the Ottoman Empire. The onset of conservation measures, modern settlement and farming activities, afforestations and a decrease of uncontrolled grazing activities and wood cutting sufficed to induce significant vegetation recovery in the semi-arid to sub-humid areas north of Qiriat Gat into the Judean Mountains. In the areas under Jordanian control no such recovery was induced, creating what is called the green line (Fig. 16), a distinct border between degraded desert in Jordan and recovering woodland vegetation on the Israeli side. This contrast has not been overcome during Israeli military administration of the West Bank since 1967, as JNF-KKL mostly avoided actions across the ‘Green Line”.

Fig. 16: the green line (the red line in this satellite image) is not only the political and security border between Israel and the Israeli administered West Bank, it is also an ecological border between somewhat recovered semi-arid vegetation on the Israeli side, and completely degraded waste land in the West-Bank.

Further evidence on the still existent state of degradation of Israel’s environments can be gained by assessing fenced, inaccessible land areas. Looking at the satellite photograph of a fenced army base reveals a distinct line of rich wadi vegetation within the fenced area, compared to completely bare land outside of the fence. This indicates that all of Israel still is heavily degraded, and that a few dozen years of conservation suffice to restore partial ecosystem function and rehabilitation (Fig. 17).

Nevertheless even dozens of years of conservation do not permit full ecosystem recovery. The only conclusion of this observation is that for thousands of years, the Middle East’s ecosystems have been exposed to the onslaught of migrating herds, unsustainable farming technologies, deforestation and unsustainable levels of resource extraction to result in a profoundly and almost irreversibly degraded ecosystem. The major difference between the recovered wasteland in Fig. 17 and the most productive woodland systems observed and described by the authors is the complete absence of dryland trees. Indeed, the dynamics of tree populations in the Negev is extremely slow. For example a small Acacia population observed near Beer Sheva has been expanding by about 1000 m into two directions during the last 30 years, growing from 1 mother-tree to a 5 tree population so far. Populations of Ziziphus spina christe expand somewhat faster, but strictly into the downstream direction and only in or along dry valleys. Consequently spontaneous population recovery of tree populations would require hundreds or thousands of years, a time span that has never been offered to the Negev’s vegetation during the last 10000 years. Therefore the recovery work as that done by Project Wadi Attir, where 20 native dryland tree and shrub species have been re-introduced, are the only way to induce the germs for possible spontaneous spreading and more rapid recovery towards the original ecosystem composition of the Negev. On the other hand, flooding the Negev with massive numbers of non-native and ecologically harmful tree species is likely not to promote ecosystem recovery in the way intended.

Have processes of historical land degradation and their consequences been scientifically documented?

Evidence for massive land degradation, erosion and desertification is widely reported throughout historical sources, archeological or paleo-biological research such as fossil pollen analysis, allowing to reconstruction past vegetation composition. Historical sources as well as 20tiest century scientific and ecological observation have allowed to directly correlate human activity with either land degradation and desertification, or land recovery and ecosystem restoration. One of the earliest direct written statements describing human induced desertification in Greece is certainly a paragraph in Plato’s discourse ‘Critias’, that describes in very short but precise terms the causal interaction between deforestation in the Greek hills and the resulting erosion and desertification creating huge areas of exposed rocky hillslopes all across the Mediterranean basin (Fig. 18). Interestingly Fig. 18 similarly provides experimental proof of Plato’s observations, demonstrating that by reforestation of semi-arid desert a new fertile, diverse and productive ecosystem can be recreated, in no more than 20 – 30 years and at low cost.

More complex archeological and scientific research has been performed to investigate the demise of various cultures thousands of years ago. More recently, during the 20tiest century the massive deforestation across the Horn of Africa (Eritrea, Ethiopia, Somalia, and Kenya) have provided a glaring example of mismanagement of the land and its dire consequences.

The following two reports strengthen and confirm all our observations, and give this subject a global significance:

Researchers insist evidence abounds in Africa that restoring forests and planting trees on farms can greatly improve food security

NAIROBI, KENYA (12 SEPTEMBER 2011)—Restoring and preserving dryland forests and planting more trees to provide food, fodder, and fertilizer on small farms is a critical step toward preventing the recurrence of the famine now threatening millions of people in the Horn of Africa, according to forestry experts from the CGIAR Consortium.

Across the Horn drought-induced famine has claimed tens of thousands lives and swelled refugee camps in Kenya, Ethiopia and elsewhere with millions of starving people—many of them children. Bearing the brunt of the crisis is Somalia, which not coincidentally is also a country that has lost a significant amount of its forests.

Experts say forest destruction and other forms of human-caused land degradation have done far more than the drought to turn vast areas of once grazeable and farmable land into a lunar-like landscape.

“Forests and trees frequently form the basis of livelihood diversification, risk-minimization and coping strategies, especially for the most vulnerable households such as those led by women,” said Frances Seymour, Director General of the CGIAR’s Center for International Forestry Research (CIFOR). “However, deforestation and land degradation have hindered capacities to cope with disasters and adapt to climate variability and change in the long-term.”

New research by CIFOR carried out in 25 countries worldwide has shown that forests serve as a crucial defense against poverty, providing about a quarter of household income for the people living in or near them. Forests in perennially parched areas of the Horn are critical to retaining moisture and nutrients in the soil while offering a bulwark against wind erosion. They also provide sources of food and fuel, particularly in tough times.

“There is a mistaken view that because these are dry areas, they are destined to provide little in the way of food and are simply destined to endure frequent famines,” said Dennis Garrity, Director General of the World Agroforestry Centre (ICRAF). “But drylands can and do support significant crop and livestock production. In fact, the famine we are seeing today is mainly a product of neglect, not nature.”

Forest and agroforestry experts say the famine should prompt significant new investments in proven approaches to reforestation and agroforestry that elsewhere in Africa are restoring forests as protectors of drylands and providing important sources of food and other valuable agriculture products.

For example, in Niger, a program launched in 1983 has transformed 5 million hectares of barren land into agroforests. ICRAF experts found that during the drought that hit the country in 2005, farmers who embraced agroforestry were able to sell trees for timber and use the money to buy food. They also were able to supplement their diets with fruits and edible leaves harvested from drought-resistant trees.

In Ethiopia, reforestation projects known as Farmer Managed Natural Regeneration (FMNR) implemented by the World Bank and World Vision are restoring some 2,700 hectares of degraded land. The projects already are providing income-generating wood and tree products for local communities, improving pasture, and achieving a drastic reduction in soil erosion.

Meanwhile, using trees in a wider variety of farm applications is rapidly making agroforestry a popular approach to improving food production in the drylands of Africa. So-called “fertilizer trees” that capture nitrogen from the atmosphere and deposit it into the soil are being used to restore degraded farmlands in Malawi, Zambia, Kenya, Tanzania, Niger, and Burkina Faso.

There are also a wide range of naturally growing trees suitable for livestock consumption that have long been used by livestock keepers in sub-Saharan Africa, particularly in the dry season when grass and crop residues are scarce.

“We need to pay far more attention to the role of forests and trees to serve both as protectors of productive farm lands and as ways to sustainably and substantially increase food security in the Horn,” said Lloyd Le Page, CEO of the CGIAR Consortium, who sees the food crisis in the region as a call to action for agricultural innovation. He noted that the intensified focus on the link between forests and food security is part of a wider effort within the CGIAR to approach farms as agriculture ecosystems that depend upon and contribute to the health of broader landscapes.

Scientists are concerned that despite clear evidence of their benefits—and of the disasters that occur in the wake of their loss—dryland forest protection and restoration is receiving scant attention compared to humid forest preservation. They point out that this disparity is particularly evident within discussions of climate change adaptation and mitigation.

“It’s ironic that dryland forests are not front and center in the climate change debate, because climate change is likely to bring more frequent and more severe droughts to dryland areas, and the adaptation challenge for affected communities will be great,” Seymour said.

She also noted that protection of both dryland and humid forests can reduce the likelihood of future climate change-induced droughts through mitigation of forest-based greenhouse gas emissions. Humid forests in particular serve as vast “sinks” that absorb and store carbon and thus help slow the pace of climate change in the long term, but there are also many opportunities to maintain and enhance the amount of carbon stored in dryland landscapes…

Case Study #2: Deforestation Making Somalia Famine Worse, Forestry Experts Say

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