An Analysis of Desertification

With Particular Focus on the “Great Green Wall of China”

UP 232 Disaster Management and Response

Professor Commins

Ryan Sclar

June 15, 2015

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Introduction

Humanity currently faces many challenges. Some of these problems are well publicized;

stories about terrorism, climate change, and disease outbreaks, for example, commonly make

the headlines. While these issues are important and often deserve the attention they receive,

equally monumental problems can frequently go unnoticed. Desertification is one of these

underestimated issues. Few people even know the meaning of the word, let alone its

implications. This paper provides an overview of desertification, describes the problems

associated with it, and analyzes some of the ways that countries are attempting mitigate its

impacts.

What is Desertification?

Definition

Desertification is a process of land degradation in dry climates. While there is debate

over exactly what constitutes desertified land, Agenda 21 provides one of the most accepted

definitions (Kassas, 1995). According to Agenda 21, desertification is, “land degradation in arid,

semi-arid and dry sub-humid areas resulting from various factors, including climatic variations

and human activities.” Terms like “desert encroachment” often conjure up images of expanding

deserts aggressively colonizing surrounding land; however, this notion is misguided (Kassas,

1995; Schleeter, 2013). While it is true that bodies of sand can extend past their climatic limits

(especially in China, as discussed later), most desertification is caused from the ground up, by

changes in climate, soil content, water levels, and vegetation (Abahussain et. al, 2002).

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Water plays a crucial role in defining desertification. The expansion of deserts occurs in

drylands, areas with less water income (precipitation) than water expenditure (evaporation and

plant consumption) (Kassas, 1995). Drylands are commonly classified by their aridity, the

severity of the deficit in their water levels. Arid areas covers 12% of the land surface of the

earth, and total dryland ecosystems account for 33% of all land (Schlesinger, 1990). These

regions are disproportionally in Africa and Asia (Figure 1).

The Causes of Desertification

Desertification is caused by several factors. Essentially, any action which degrades dry

land leads to desertification. Human activities, such as livestock grazing, crop cultivation, and

mining can create desertified land if conducted in an unsustainable fashion (Schlesinger, 1990;

Africa Asia Australia Europe North America South America

Hyper-arid 672 277 0 0 3 26

Arid 504 626 303 11 82 45

Semi-arid 514 693 309 105 419 265

Dry sub-humid 269 353 51 184 232 207

DRYLAND BY CONTINENT (MILLION HECTARES)

Figure 1: Dryland by Continent (Million Hectares) Source: Data from Kassas, 1995

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Kassas, 1995; Runnström, 2000). In general, the classic “tragedy of the commons” scenario is

the main culprit for land degradation. Figure 2 shows the findings of Zha and Jay (1997)

describing how different human activities relate to desertification. While the preciseness of

these data is debated, most literature agrees that overgrazing and over cultivating as the chief

culprits in human-led desertification (Tan et. al, 2014; Schlesinger, 1990). These activities can

lower the water table, create erosion and degrade soil content.

Drylands can also succumb to desertification by natural causes. Periods of below

average rainfall can be just as detrimental to water tables as agriculture (Kassas, 1995). Arid

areas subjected to sandstorms1 and invasive desert shrubs can be exposed with thinner plant

coverage. This lowers bioproductivity and prevents soil development (Schlesinger, 1990).

Identifying which aspects of desertification are human-caused and which are natural is difficult.

1 For simplicities sake, this study assumes the terms “sandstorm” and “dust storm” to be equal and uses them interchangeably.

Over Cultivation

Overgrazing

Excessive Collection of

Wood

Mining and Construction

Estimated Human Contributions to Desertification

Figure 2: Estimated Human Contributions to Desertification Source: Zha et. al, 1997

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Estimates range dramatically, however many researchers believe that human activities are to

blame for 60% to 90% of modern desertification (Zha et. al, 1997).

The Problem

Desertification has the potential to impact many people in several different parts of the

world. Drylands are home to over two billion people, about 30% of the human race (Stringer,

2008). As people conglomerate in cities in arid regions, development is often pushed forward

unsustainably, permanently degrading the productive capacity of that land (Schlesinger, 1990).

This results in ecological deterioration as well as economic loss. Abahussain et. al, (2002)

describe the downward spiral created by this problem. Reductions and fluctuations in yields

from woodlands, pastureland, and agriculture make farming less predictable, which can lead to

food insecurities. These uncertainties lead people to panic and overexploit their land even

more, which further exacerbates the desertification process. Every year 200,000 square

kilometers are claimed to be abandoned due to desertification (Abahussain et. al, 2002). 35% of

the world’s land surface is at risk for future degradation (Helldén, 1991). Through food

insecurities, desertification can cause malnutrition, diseases, social disorder, and even death

(Olsson, 1993).

In understanding the problems associated with desertification, it is important to note

the complicated relationship between desertification and food insecurity. Not all food

insecurity is caused by desertification and not all deserts disallow the cultivation of food. There

are some pastoral societies which have long lived and prospered in desert climates. Some

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believe that policy makers place too much emphasis on the role of desertification, and often

use it as a scapegoat for other problems. Olsson (1993) claims, for example, that the 1984-1985

famine in Sudan was primarily caused not by a desert-led decline in food availability, but by a

broken relationship between people and food (there was enough food on the national level but

speculation and inadequate distribution brought on the famine). Desertification is responsible

for many ecological, economic, and health problems, but should be analyzed with the role of

exogenous variables in mind.

Efforts to Manage Desertification in the International Community

The first major attempts by the international community to study desertification took

place in the mid-20th century. The United Nations Educational Scientific and Cultural

Organization (UNESCO) initiated a program in 1950 to establish 200 arid zone research

institutions throughout the world. From this effort, over 30 volumes of scientific and technical

reports were published to allow the causes and effects of desertification to become better

understood by policy makers (Kassas, 1995). In the late 1960’s and early 1970’s prolonged

problems in the Sahel region of Africa intensified the discussion over desertification.

The United Nations (UN) began to think more critically about desertification in the

1970’s. In 1975, ecologist Huge Lamprey popularized the current “desert encroachment theory”

in a United Nations Environmental Program (UNEP) report on the African Sahel region (Yang et.

al, 2005). Lamprey’s claim that the southern boundary of the Sahara desert had shifted by 100

kilometers over the past two decades astounded many in the international community. Two

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years later the UNEP held a Conference on Desertification, declaring it to be one of the major

environmental problems of our time (Helldén, 1991). This conference brought about much of

the existing research on desertification and on ways to rehabilitate land (Zha et. al, 1997).

The issue of desertification has been on the agenda of the UN General Assembly since

the 1970’s. The Plan to Action to Combat Desertification (PACD) funded projects and research

through the 1990’s, and the UN Convention to Combat Desertification ratified an additional

plan in 1996 (Kassas, 1995; Zha et. al, 1997). The UN General Assembly even named 2006 the

International Year of Deserts and Desertification. In doing so, the UN established four

objectives, although these did little to engage in concrete measures to mitigate desertification.

The UNEP recommends allocating $10 billion to $22 billion per year towards mitigating

desertification (although recent funds totaled less than $1 billion annually) (Stringer, 2008). The

UN recognizes desertification as a very serious issue, but international mitigation efforts have

been minimal.

Desertification in Africa

Most of the desertification related studies and programs initiated by the UN and others

have been specifically targeted towards the African Sahel Region. While the expansion of

deserts is a worldwide issue, Africa is home to some of the largest and harshest climates (Figure

1). The Sahel region has also hosted several infamous famines in past decades, drawing more

attention from world policy makers than other deserts in Asia and elsewhere (O’Connor and

Ford, 2014). Many of these endeavors center upon the management of droughts. Programs

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through the UN and the World Meteorological Organization use satellite imagery to forecast

rainfall and drought prone areas, as does USAID’s Famine Early Warning System (Kassas, 1995).

Many programs have also aimed to increase societal preparedness, educating farmers on

sustainable farming techniques and drought resistant practices. Most of the efforts to prevent

desertification in Africa take the form of predictions and preparation measures.

The largest and most ambitious plan to fight desertification in Africa is the so called

Great Green Wall (GGW)2. This project involves the planting of a continuous 15 kilometer-wide

row of trees, spanning 7,775 kilometers across the continent (Schleeter, 2013) (Figure 3). The

concept behind the GGW is that a “wall” of trees from Senegal to Djibouti will naturally

moderate temperatures, wind speed, soil erosion, and humidity. This GGW was initially

proposed in the early 1980’s, and recently subject to bolstered interest in the wake of

intensifying climate change discussions (O’Connor et. al, 2014). Despite controversy, this

2 This is also often referred to as the Green Great Wall; to avoid confusion, this paper will only use the term Great Green Wall.

Figure 3: The Proposed Great Green Wall of Africa Source: Constructed with data from O’Connor et. al, 2014

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project was officially ratified at the World Day to Combat Desertification and Drought in 2002,

with the support of all of the 11 countries which the project would span.

Although the GGW is endorsed by every country in the Sahel, its implementation has

been squandered by a lack of both funds and coordination. Currently only $115 million of the

proposed multiple billion dollar3 project is securely financed (Schleeter, 2013). Most of this

money has been spent in Senegal and Niger, where work on the project has started in a

piecemeal fashion (O’Connor et. al, 2014). The lack of a powerful central authority has also

stunted the progress of the GGW. The UNEP has stressed the need for regional entities,

national governments, and local communities to better collaborate on the GGW in order to

make any real progress (O’Connor et. al, 2014).

Desertification in China

China’s Challenges

While most of the international anti-desertification efforts have been geared towards

Africa, China also faces a formidable task securing its arid land against degradation. By some

measures, China is the most severely desertified country in the world. 13% of China’s 9.6

million square kilometers is desert (Zha et. al, 1997). 23% of the country is classified as

drylands, vulnerable to desertification (Veste et. al, 2006). Northern China, home to both the

Takla Makan and Gobi deserts, also supports the world’s largest population of grazing animals

3 Due partially to the lack of cooperation, no agencies are able to provide an accurate estimate of the total cost of constructing the GGW.

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(Runnström, 2000). It is estimated that 2,460 square kilometers of land and $800 million in

Northern China are lost each year to overgrazing (Levin, 2005). The region also faces the

challenges of deforestation and drought. China has 7% of the world’s arable land to feed 22% of

the world’s population (Piao et. al, 2010). Desertification is a pressing issue in China.

China faces unique challenges due to the nature of their dust storms. In the 1950’s, the

country averaged 5 major sandstorms per year. In 2000, there were 8 such events in just a 45

day period (Veste et. al, 2006). Sand and dust storms cause more challenges in China than

anywhere else because of the country’s immense concentrations of people. These storms

impact large areas of the country, affecting many of the nation’s largest cities and hundreds of

millions of inhabitants.

These shifting sand

dunes and high winds

interfere with

irrigation, railway, and

highway

infrastructure, and can

severely impact the

economy. Dust storms are more than just an inconvenience; on just one day in 1993 a cloud a

dust injured 264 people and killed over 85 people and 100,000 livestock (Veste et. al, 2006).

These storms transport large enough quantities of sand that they can desertify areas which

otherwise have enough rainfall and temperature moderation to facilitate life. Many areas in the

Tengger desert, for example, are only classified as desert because their high wind speeds

Figure 4: Beijing during a sandstorm (left) and on a regular day (right) Source: “China’s Great Green Wall,” 2015

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transport layers of migratory sands. For all intents and purposes, Chinese sandstorms are just as

detrimental, if not more so, as conventional storms.

China also faces a challenging erosion problem. The Loess Plateau is commonly referred

to as the most erosion prone place on earth (Tian et. al, 2000). This region was once 15%

covered by forest during the Ming Dynastic several hundred years ago. During the early 20th

century, extensive logging accompanied rapid development in the region. By 1949, only 3% of

the Loess Plateau was forested (Veste et. al, 2006). Greenpeace estimates that now only 2% of

China’s original forests are still intact (“Afforestation in China,” 2014). This, combined with the

steep slopes of the terrain leads to large scale soil erosion. Estimates vary significantly, but it is

believed that between 1,100 and 9,600 tons of soil in every square kilometer are lost to erosion

each year on the Loess Plateau (Veste et. al, 2006). The Yellow River derives its name (and its

color) from the immense amount of eroded dirt that washes into it. In addition to the erosion

of soil, other types of erosion also play a nontrivial role in the degradation of land in northern

China (Figure 5). The erosion problems of China are arguably unrivaled by anywhere else in the

world.

0

0.5

1

1.5

2

Soil Physical/ Chemical Erosion Water Erosion Salinization

Are

a (M

illio

n S

qu

are

Kilo

met

ers)

Land Lost to Erosion in Northern China

Figure 5: Land Lost to Erosion in Northern China Source: Zha et. al, 1997

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Effort to Manage Desertification and the Great Green Wall

Given the detrimental effects that dust storms and erosion inflict on the stability of the

country, the Chinese government has taken several steps to mitigate desertification. As with

the UN, China began to think prudently about the impacts of desertification during the latter

half of the 20th century (Runnström, 2000). One of the earliest environmental laws in China was

a product of the negative impact that foresting was having on the Loess Plateau. By the late

1970’s there were several environmental acts drafted at the national level. The Household

Production Responsibility Act, introduced in the mid 1980’s, attempted to dramatically increase

the amount of fenced pasture areas to prevent overgrazing4 (Runnström, 2000). In 1991, the

Chinese government initiated the China Desertification Rehabilitation and Desert Reclamation

Action Program, which led to a round of comprehensive environmental laws and several

engineering projects aimed at combating sandstorms and erosion (especially along corridors

with major infrastructure connections) (Veste et. al, 2006).

4 This act was slightly controversial; some claim it was not properly implemented or enforced.

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Without a doubt, the capstone in China’s fight against desertification is their Great

Green Wall Plan. Similar to plans in the African Sahel region, China proposed to obstruct

desertification with of a belt of vegetation. This plan was one of the first acts by the then new

leader of China, Deng Xiaoping (Levin, 2005). This comprehensive project detailed a series of

windbreaks, shelterbelts, and sand dune stabilization efforts in three stages of eight sections. At

the heart of this plan was the Three Norths5 Protective Forest System, also known colloquially

as the “Great Green Wall of China.” This barrier was proposed to span 4480 kilometers across

the country, acting as a primary line of defense against sand and dust storms (Veste et. al,

2006) (Figure 6). The Chinese government claims the project will afforest 4 million square

5 Three Norths refers to the three regions of the country the project would be constructed through – the Northwest Region, the Northern Region, and the Northeast Region.

Figure 6: The Proposed Great Green Wall of China Source: Constructed with data from Tan et. al, 2014

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kilometers, 42% of all land in the country, by its completion in 2050. While this projection is

controversial and may need to be taken with a grain of salt, this is clearly an enormous

undertaking. In fact, the GGW is currently the largest ecological project in the history of

humankind (Levin, 2005). By almost all measures, this plan is ambitious.

Unlike the GGW in the Sahel, China’s GGW project has significant political and economic

backing. China has implemented this project with a very top down approach, with most of the

planning being done at the national level. The first of the three stages has already been

officially declared finished6 and the project continues to move forward. Government officials

state that 24 million hectares of trees and other vegetation have been planted so far as part of

6 The first stage was completed in 2001, however it was originally intended to be finished in 1985.

Figure 7: Typical Segment of the Great Green Wall Source: Data from Levin, 2005

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the Three Norths Protective Forest System (Levin, 2005). The State Forestry Administration

claims that a total of 50 million hectares of forests have been seeded across China throughout

all of their shelterbelt programs. This equates to roughly 66 billion trees (“Afforestation in

China,” 2014). Regardless of whether one thinks this plan is worthwhile, the GGW certainly

represents a very large political endeavor.

The Chinese government has also proven its willingness to invest monetarily in the

GGW. While the total price of completing the 73 year project is uncertain, the government

estimates that it costs roughly $1.9 billion per year7 (“China’s Great Green Wall,” 2001). China

has also poured an additional $1.2 billion into an oversight system to map, survey, and protect

the project8 (Levin, 2005). Backers of the GGW say it’s worth the steep price tag because it will

protect 8.5 million hectares of farmland and increase grain yield by 5.5 million tons (Zha et. al,

1997). Some Chinese politicians have claimed the project has already paid off, crediting

Beijing’s successful 2008 Olympic bid in part to the GGW showing China’s commitment to

prevent dust storms in Beijing (“China’s Great Green Wall,” 2001). Zha et. al (1997) take a

slightly more cynical perspective, declaring that, “The history of rehabilitating desertified land

in China is essentially the history of converting it into productive uses in sandy areas” (Zha et.

al, 1997). Either way, the Chinese government has provided significant financial backing to their

GGW.

7 This number comes from a reference published in 2001 and has been adjusted for inflation to 2015 dollars. 8 Part of this money comes from foreign investors, including the World Bank, the UN Development Program, and the UN Food and Agricultural Organization.

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Does the Great Green Wall Work?

There is significant debate regarding the overall worthwhileness of China’s GGW; the

project has successfully achieved some promising results and unequivocally failed to deliver on

other objectives. Opinions, both inside and outside of China, are still very much divided on the

outcomes and fate of this project. Given the proposed completion year of 2050, discussions

surrounding the GGW are ongoing and prone to change.

Pros

There is little doubt that China has more vegetation now than it did when the project

commenced in 1978. Runnström (2000) analyzed satellite imagery and the Normalized

Difference Vegetation Index determining that the GGW was successful in increasing the amount

of nearby vegetation. The study concluded by optimistically noting, “…the extensive land

reclamation activities throughout China that are hoped to reverse decades of environmental

misuse are beginning to pay off” (Runnström, 2000). Nevertheless, this study was cautious,

disclaiming that this increase in vegetation did not necessarily correspond to an increase in the

carrying capacity of the land. Zha et. al (1997) corroborated this finding that vegetation had

increased, stating that forest coverage in China increased form 5.05% to 7.09% of total land

area during the first decade of the project. Other literature comes to similar conclusions; the

drylands in China are generally getting greener.

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Perhaps the most significant achievement of the GGW is that it does seem to be abating

dust storms. These storms can clog infrastructure, lead to respiratory problems, and carry the

desert past the natural boundaries of its ecosystem. Storms of dust and sand are the only real

aspect of desertification that directly impact the big cities population centers. Not only does

this make the eradication of these storms important, but also politically pressing. For these

reasons, mitigating the severity and frequency of dust storms was one of the primary objectives

of the GGW project. Tan et. al (2014) analyzed dust storms data from the past four decades and

concluded that these storms have been diminishing in intensity and frequency since the late

1970’s. “…The implementation of the GGW programme has effectively decreased [dust storm

Figure 8: Before (Top) and After (Bottom) GGW Implementation Source: United Nations Convention to Combat Desertification Website

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intensity] by improving the vegetation conditions” (Tan et. al, 2014). Zhang et. al (2008) came

to similar conclusions. Whether or not this drop in dust storms is related to the GGW or some

other factor, dust storms are currently less problematic than they have been in years past.

Cons

While vegetation has increased overall, much of the planted forests are not surviving.

The Chinese government refuses to publicize information on tree survival rates, even to

international agencies funding its oversight efforts (Levin, 2005). Estimates range wildly, and

most likely depend on the specifics of the location. Runnström (2000) estimates that only 40%

of trees survive. Others think less than a quarter of the trees live to maturity. These low survival

rates are often blamed on China’s use of monocultures, which are more vulnerable to climate

change, disease, herbivory, and pests (Veste et. al, 2006). In 2000, a pest in the northwest

region was able to kill 1 billion trees, representing several years of planting efforts. Lack of

water is another reason the trees do not survive. Critics claim that these artificial forests can

deplete groundwater sources, killing themselves off, as well as any previously existing

vegetation. Even when the trees do survive, the natural life cycle of most of these trees is only

40 years – about half the time that the GGW will likely take to complete (“Afforestation in

China,” 2014). By the time the project is finished in 2050, it is possible that half of the trees will

already be dead of natural causes. It is uncertain that China will ever be able to actually

complete the GGW project.

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The GGW may benefit the land on the fringe of the desert, but its impact on the people

who live in these regions is not particularly positive. The decision-making process for

implementing the GGW is very top down, and the locals, who are the most directly affected,

often have little to no say. Although residents are offered cash incentives to help plant the

trees, several of the areas with higher levels of precipitation are planted by aerial drops,

bypassing the locals. Some farmers have seen their agricultural land and pastures turned into

giant tree monocultures, with little visible benefit to them (O’Connor et. al, 2014). These trees

can also drain the water table, drying out wells and making it more difficult to irrigate crops. In

some extreme cases, China has even forcibly relocated people in areas with extreme erosion

(“Afforestation in China,” 2014). If one of the main goals of the GGW is to provide stability for

people living in desertification-prone regions, the GGW is arguably failing at this task.

Conclusion

Desertification is a problem which affects many areas of the world, especially in Africa

and Asia. Since the late 1970’s, countries have attempted to abate this problem, with China

leading the charge with their GGW - the largest ecological project in the history of humankind.

At this time, there is no consensus on the level of success the GGW has achieved. As the plan

moves closer to its 2050 finish date, the lessons learned from the GGW will likely become more

obvious. The world will be eagerly watching to see if China’s ambitious fight against

desertification pays off. If it does, the implications would be momentous, and perhaps one day

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the Great Green Wall of China could carry more historical significance than the actual Great

Wall of China itself.

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