IPCC Fourth Assessment Report: Climate Change 2007
Climate Change 2007: Working Group II: Impacts, Adaptation and Vulnerability

5.4.7 Rural livelihoods: subsistence and smallholder agriculture

The impacts of climate change on subsistence and smallholder agriculture, pastoralism and artisanal fisheries were not discussed explicitly in the TAR, though discussion of these systems is implicit in various sections. A number of case studies of impacts on smallholder livelihood systems in developing countries are beginning to appear, some focussed on recent and current climate variability seen within a climate change context (Thomas et al., 2005a), others using modelling approaches to examine future impacts on key smallholder crops (Abou-Hadid, 2006; Adejuwon, 2006) or ecosystems used by smallholder farmers (Lasco and Boer, 2006). In some cases impacts are discussed within work focussed more on adaptation (Thomas et al., 2005a).

Specific impacts must be examined within the context of whole sets of confounding impacts at regional to local scales (Adger et al., 2003). It is difficult to ascribe levels of confidence to these confounding impacts because livelihood systems are typically complex and involve a number of crop and livestock species, between which there are interactions (for example, intercropping practices (Richards, 1986) or the use of draught-animal power for cultivation (Powell et al., 1998)), and potential substitutions such as alternative crops. Many smallholder livelihoods will also include elements such as use of wild resources, and non-agricultural strategies such as use of remittances. Coping strategies for extreme climatic events such as drought (Davies, 1996; Swearingen and Bencherifa, 2000; Mortimore and Adams, 2001; Ziervogel, 2003) typically involve changes in the relative importance of such elements, and in the interactions between them. Pastoralist coping strategies in northern Kenya and southern Ethiopia are discussed in Box 5.5.

Box 5.5. Pastoralist coping strategies in northern Kenya and southern Ethiopia

African pastoralism has evolved in adaptation to harsh environments with very high spatial and temporal variability of rainfall (Ellis, 1995). Several recent studies (Ndikumana et al., 2000; Hendy and Morton, 2001; Oba, 2001; McPeak and Barrett, 2001; Morton, 2006) have focussed on the coping strategies used by pastoralists during recent droughts in northern Kenya and southern Ethiopia, and the longer-term adaptations that underlie them:

  • Mobility remains the most important pastoralist adaptation to spatial and temporal variations in rainfall, and in drought years many communities make use of fall-back grazing areas unused in ‘normal’ dry seasons because of distance, land tenure constraints, animal disease problems or conflict. But encroachment on and individuation of communal grazing lands, and the desire to settle to access human services and food aid, have severely limited pastoral mobility.
  • Pastoralists engage in herd accumulation and most evidence now suggests that this is a rational form of insurance against drought.
  • A small proportion of pastoralists now hold some of their wealth in bank accounts, and others use informal savings and credit mechanisms through shopkeepers.
  • Pastoralists also use supplementary feed for livestock, purchased or lopped from trees, as a coping strategy; they intensify animal disease management through indigenous and scientific techniques; they pay for access to water from powered boreholes.
  • Livelihood diversification away from pastoralism in this region predominantly takes the form of shifts into low-income or environmentally unsustainable occupations such as charcoal production, rather than an adaptive strategy to reduce ex-ante vulnerability.
  • A number of intra-community mechanisms distribute both livestock products and the use of live animals to the destitute, but these appear to be breaking down because of the high levels of covariate risk within communities.

Impacts of climate change upon these systems will include:

  • The direct impacts of changes in temperature, CO2 and precipitation on yields of specific food and cash crops, productivity of livestock and fisheries systems, and animal health, as discussed in Sections 5.4.1 to 5.4.6 above. These will include both impacts of changing means and increased frequency of extreme events, with the latter being more important in the medium-term (to 2025) (Corbera et al., 2006). Positive and negative impacts on different crops may occur in the same farming system. Agrawala et al. (2003) suggest that impacts on maize, the main food crop, will be strongly negative for the Tanzanian smallholder, while impacts on coffee and cotton, significant cash crops, may be positive.
  • Other physical impacts of climate change important to smallholders are: (i) decreased water supply from snowcaps for major smallholder irrigation systems, particularly in the Indo-Gangetic plain (Barnett et al., 2005), (ii) the effects of sea level rise on coastal areas, (iii) increased frequency of landfall tropical storms (Adger, 1999) and (iv) other forms of environmental impact still being identified, such as increased forest-fire risk (Agrawala et al., 2003, for the Mount Kilimanjaro ecosystem) and remobilisation of dunes (Thomas et al., 2005b for semi-arid Southern Africa).
  • Impacts on human health, like malaria risk (see Chapter 8, Section, affect labour available for agriculture and other non-farm rural economic activities, such as tourism (see Chapter 7, Section

For climate change impacts on the three major cereal crops grown by smallholders, we refer to Figure 5.2a-f and discussion in Sections 5.4.2 and 5.5.1. In Section 5.4.1 above we discuss the various negative impacts of increases in climate variability and frequency of extreme events on yields (see also Porter and Semenov, 2005). Burke et al. (2006) demonstrate the risk of widespread drought in many regions, including Africa. Projected impacts on world regions, some of which are disaggregated into smallholder and subsistence farmers or similar categories, are reviewed in the respective regional chapters. An important study by Jones and Thornton (2003) found that aggregate yields of smallholder rain-fed maize in Africa and Latin America are likely to decrease by almost 10% by 2055, but these results hide enormous regional variability (see also Fischer et al., 2002b) of concern for subsistence agriculture.

With a large body of smallholder and subsistence farming households in the dryland tropics, there is especial concern over temperature-induced declines in crop yields, and increasing frequency and severity of drought. These will lead to the following generalisations (low confidence):

  • increased likelihood of crop failure;
  • increased diseases and mortality of livestock and/or forced sales of livestock at disadvantageous prices (Morton and de Haan, 2006);
  • livelihood impacts including sale of other assets, indebtedness, out-migration and dependency on food relief;
  • eventual impacts on human development indicators, such as health and education.

Impacts of climate change will combine with non-climate stressors as listed in Section 5.2.2 above, including the impacts of globalisation (O’Brien and Leichenko, 2000) and HIV and/or AIDS (Gommes et al., 2004; see also Chapter 8).

Modelling studies are needed to understand the interactions between these different forms of climate change impacts and the adaptations they will require. The multi-agent modelling of Bharwani et al. (2005) is one possible approach. Empirical research on how current strategies to cope with extreme events foster or constrain longer-term adaptation is also important (see Davies, 1996). Knowledge of crop responses to climate change also needs to be extended to more crops of interest to smallholders.

Many of the regions characterised by subsistence and smallholder agriculture are storehouses of unexplored biodiversity (Hannah et al., 2002). Pressure to cultivate marginal land or to adopt unsustainable cultivation practices as yields drop, and the break down of food systems more generally (Hannah et al., 2002), may endanger biodiversity of both wild and domestic species. Smallholder and subsistence farming areas are often also environmentally marginal (which does not necessarily conflict with biodiversity) and at risk of land degradation as a result of climate trends, but mediated by farming and livestock-production systems (Dregne, 2000).