ALN logo; link to Arid Lands Newsletter home page No. 49, May/June 2001
Linkages between Climate Change and Desertification

Linkages between climate change and desertification in East Africa
Part 1: Physical and social linkages

by Siri Eriksen

"The measures briefly outlined in this article represent a means of addressing global environmental concerns while also enhancing basic local survival."


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In this article, it is argued that policy measures aimed at ameliorating the effects of climate change can effectively build on measures to combat desertification. The article looks at how the global issues of climate change and desertification can be effectively addressed at the local level in sub-Saharan Africa, by presenting presents results from research carried out through case studies in two dryland areas: Same District in Tanzania and Kitui District in Kenya, further described in Eriksen (2000). The first part of the article focuses on physical and social linkages. This question is approached by distinguishing physical and social linkages between these issues at the local level and investigating how these local linkages are reflected in local action and livelihood options. The second part of the article reviews how the local linkages and related actions are incorporated into government policies.

The policy relevance of linkages between climate change and desertification

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Climate change and desertification are perceived differently in terms of their impact. Climate change is viewed as taking place within a global-scale environmental system, while desertification is often viewed as widely dispersed effects of local environmental degradation. Consequently, different types of measures have been suggested to combat each problem. Desertification measures have targeted local resource use and livelihoods; climate change remediation efforts have focused on reducing global greenhouse gas emissions. As more attention is gradually being paid to climate adaptation and ameliorating local impacts of climate change, however, climate measures and desertification measures at the local level may increasingly complement each other.

Many African countries are committed to the two international conventions aimed at these problems: the United Nations Framework Convention on Climate Change (Climate Convention) and the United Nations Convention to Combat Desertification in Those Countries Experiencing Serious Drought and/or Desertification, Particularly in Africa (Desertification Convention or CCD). In this regard they are committed to reforming policies and drawing up plans and strategies to combat local manifestations of these two global phenomena.

table comparing UNFCCC and UNCCD
Thumbnail link to table comparing UNFCCC and UNCCD

The need to coordinate measures to implement both conventions can be viewed from two perspectives. First, implementation of such measures may affect local welfare. Rural households represent a large majority of the population in sub-Saharan Africa. In Kenya, for example, 80% of the population live in rural areas (Republic of Kenya 1997b, p. 12). It follows that enhancing the social and economic viability of these households is crucial for the welfare of a large section of the population. Rural households are in many cases the managers of local resources, and their activities are critical with regard to, for example, combating desertification. In fact, both conventions are concerned with local resources and their use. The Climate Convention aims at preventing the causes of climate change (e.g. emissions), and mitigating the adverse effects of such change. The Climate Convention recognizes the need for humans to adapt to the impacts of climate change and commits Parties to prepare for such adaptation. The Desertification Convention aims both at combating desertification, or dryland degradation, and at mitigating adverse effects of drought, with a view to achieving sustainable development in selected areas. As long as both conventions are concerned with safeguarding local welfare and resources, their efforts should be coordinated.

Second, in terms of implementation, developing countries lack resources to instigate costly programs. The need to link implementation of conventions in order to avoid duplicative or counterproductive measures is formally embodied in the convention texts. The Desertification Convention in particular explicitly states that its activities should be co-ordinated with other conventions, particularly the Biodiversity Convention and the Climate Convention. Joint programs that contribute to achieving the objectives of the agreements concerned are encouraged (CCD, Article 8). The Climate Convention, in its preamble, recalls previous UN resolutions concerned with climate change, sea level rise and desertification.

There are several possible links between the physical processes of climate change and desertification. The links between these two issues become particularly strong, however, when the local-level social context of natural resource management is taken into account.

The processes of climate change and desertification

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Climate change refers to the effect of human-induced increase in the concentration of greenhouse gases in the atmosphere, enhancing the natural greenhouse effect. Combustion of fossil fuels, cement production and land use changes have led to CO2 concentrations increasing by almost 30 percent since the 18th century. Other greenhouse gases are also increasing in concentration in the atmosphere due to human activities, mainly use of landfills, agriculture in general and rice paddy cultivation in particular, animal rearing, fossil fuel use and industrial production. These gases include methane, which has more than doubled since pre-industrial times, as well as nitrous oxide, sulphur dioxide and ozone (Schimel et al. 1996). As the concentration of these gases increases, so does the radiative forcing, and global mean surface temperature. The magnitude of the human-induced effect is not fully resolved, but surface temperature observations indicate that there has been a global mean warming of 0.3 to 0.6 degrees centigrade over the past one hundred years (Schimel et al. 1996), a very rapid rate of change compared to past changes in climate (Zinyowera et al. 1998).

The effects that a global mean change in temperature may have on local and regional scales are extremely variable and uncertain due to the influence of atmospheric circulation and ocean bodies (Mitchell and Hulme 1999). In addition to changes in the mean climatic conditions (such as temperature and rainfall), the frequencies of irregular seasons and extreme events, including fires, hurricanes and droughts, are likely to change and in some places increase (Parry 1986; Peters 1992). Given the potentially dramatic effects on local climate, natural resources, infrastructure and economic activities, Africa may be particularly physically vulnerable to and at risk from climate change.

Desertification relates to both the processes and the end state of dryland degradation, involving soil erosion, soil degradation, deforestation and degradation of the natural vegetation, as well as declining biological productivity of the land (Swift 1996). The term desertification has been associated with a number of physical manifestations, such as sand dunes, that have conjured up images of deserts expanding uncontrollably, fuelled by population growth and inappropriate resource use technologies (Mortimore 1998). However, the significance of such physical manifestations, the processes by which such manifestations are reached, and the extent to which the end state of degraded lands is temporary or permanent, have been the topics of much debate (Benjaminsen 1996; Mortimore 1998).

The effect of vegetation change on climate

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The first link between climate change and desertification concerns the suggestion that removal of vegetation, or dryland degradation, may affect the climate. The perception that desertification is a man-made process is partly based on studies, such as Charney (1975), which suggest that removal of vegetation cover affects the rainfall-producing convection circulation in West Africa, leading to a decline in rainfall over the Sahel. The rationale behind the process hypothesized by Charney is that as the vegetation and canopy cover decrease, the albedo (shortwave reflection coefficient) at the Earth's surface increases and evapotranspiration may be reduced. Increased albedo in turn leads to decreased net radiation at the surface and, in turn, reduced latent and sensible heat. Clearing of forest leads to reduced interception of rainfall and therefore a greater proportion of precipitation being lost from the local area as run-off (Henderson-Sellers et al. 1988) and less moisture being recycled back into the atmosphere through latent heat.

Model studies of the interaction between land cover and climate, such as Franchito and Rao (1992) and Varejao-Silva et al. (1998) indicate that the climate is sensitive to vegetation changes (Kutzbach et al. 1996), though the extent of the effect is uncertain, and the scale of change very regional (Chase et al. 2000). Such model studies have also attracted criticism for inputting extreme changes in vegetation parameters, thus testing the sensitivity of the climate to hypothetical vegetation changes rather than realistic changes in vegetation (Allen et al. 1994).

A second link between desertification and deforestation and the global climate system is the emission of CO2 into the atmosphere. DeFries et al. (1999) estimate that land use change has contributed at least one third of the total carbon released into the atmosphere from human activities. Deforestation also leads to a transient increase in atmospheric CO2 released by burning or decomposition of the forest biomass (Henderson-Sellers 1988). Hulme and Kelly (1993) point out that desertification reduces a potential carbon sink, in terms of carbon stored in vegetation. Though important for regional net carbon budgets, however, they suggest that land conversion in dryland areas is a less important contributing factor than tropical deforestation to carbon emissions.

The effect of climatic changes on vegetation

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Instead, previous work suggests a third important link: namely, that global climate changes exert a stronger effect on local climate patterns and desertification than the reverse. Natural climatic variability as well as global mean warming may be driving forces in desertification (Hulme and Kelly 1993). Sea surface temperatures may be a dominant factor influencing rainfall variability in general (Zheng and Eltahir 1998) and the Sahelian climate in particular (Rowell et al. 1992). Much of the variability of the Sahara's areal extent can be explained by rainfall variability. Change in rainfall patterns alters the extent of arid, semi-arid and dry sub-humid areas. Savannas, a common dryland vegetation type in Africa, are likely to be particularly affected by global climate change as their water balance and vegetation are quite sensitive to water balance changes induced by temperature and precipitation changes (Yang and Prince 2000).

Social linkages between climate change and desertification

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Significantly, while local resource management provides a link between desertification and climate change, this social context also highlights the complexity of this relationship. For example, there is a high degree of uncertainty concerning both the extent of desertification and the mechanisms by which human activities and vegetation changes interact. Lambin (1997) points out that measuring dryland degradation is particularly difficult because there is a strong interaction between erratic and natural fluctuation in rainfall and anthropogenic changes in vegetation cover. The causes and effects of soil erosion, soil degradation, degradation of the natural vegetation and deforestation are difficult to discern, and it is therefore also difficult to define or find indicators for desertification and map these on a global scale (Mortimore 1998).

Some authors have argued that the extent of the problem of desertification has been over-emphasized because of "insufficient investigation on the ground as to how environments, societies and food production systems respond to periods of drought" (Binns 1990, p. 107). Findings from a local level study by Binns (1990) suggesting little evidence of desertification in connection with the 1985 drought in Mali are corroborated by a study by Warren and Agnew (1988). Because of fluctuations in climate and vegetation, Warren and Agnew found it impossible to determine whether the condition of the Sahel at any time between 1968 and 1984 could be reliably attributed to long-term degradation or to drought.

An important aspect of the desertification debate is that the difficulties of specifying human impact against a background of natural fluctuation and paucity of data imply a need to allow for surprise and uncertainty in planning for sustainability (Turner 1988). There is no simple relationship between declining vegetation, erosion and land productivity. Acknowledgement of these uncertainties has led to a shift towards assessing degradation in terms of reduced economic output, rather than physical changes in the soil (Swift 1996). Thus, it has been suggested that environmental degradation measures should be assessed on the basis of crop yields or return on investment. Degradation can then be most usefully defined in terms of farmer livelihoods, a locally based economic definition of environmental degradation.

map of study area
Thumbnail link to map of study sites

The above definition links desertification to an important aspect of climate change: human adaptation to its effects. As part of the research reported on in this article, 50 household interviews were carried out in each of the two sites, located in Kitui District, Kenya, and Same District, Tanzania, regarding sources of livelihood and local resource use during selected time periods. Rural household responses to climatic events between 1997 and 1999 in both study sites suggested that local agro-ecosystems, in terms of on-farm and off-farm natural resources, played a crucial role in local coping with extreme events, including drought and flood. This has two main implications for linkages between climate change and desertification. First, alternative sources of livelihood are vital to climate change adaptation. Second, the extent of environmental degradation determined many people's livelihood options and ability to adapt to climate change. This relationship has important qualifications: Local coping mechanisms to climatic extremes do not directly translate into successful adaptation to climate change. Present coping mechanisms may be inadequate in dealing with future longer-scale changes.

Further, some coping mechanisms, such as cutting indigenous forest for charcoal production as an income source during drought, may contribute to environmental degradation and potentially limit future resource access and livelihood options. Such coping mechanisms have, however, been crucial to survival for many people during climatic changes that have occurred over the past decades. This is likely to hold true in the foreseeable future. Few households are reached by government programs or are currently able to adopt solutions that are labor-, technology-, or finance-intensive. In particular, the informal sector and local natural resources are important sources of food and income during harvest failure for vulnerable households, including labor poor households, households with no member employed in the formal sector, and female-headed households.

Implications for climate adaptation efforts

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Three main approaches to reducing vulnerability to climate variability are relevant for our further discussion of policy-level links between desertification and climate change. One approach is to reduce the need for household coping strategies, or ensure that harvests fail less often, by increasing the resistance of agriculture to drought and climatic variability. Some preferred coping strategies are successful in enabling households to maintain basic consumption during drought; however, only a minority of households have access to these strategies. A second approach is, therefore, to enhance household access to these preferred or principal coping strategies. A range of coping strategies was identified to which the majority of households had access, but which did not secure consumption during drought. It follows that a third way of reducing vulnerability is to increase the viability of drought coping strategies to which most households have access. Enhancing household ability to engage in alternative economic activities during drought becomes an important measure for improving climate change adaptation.

[Continued in Part 2: Policy linkages]

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