Box 54 Impact of coral mortality on reef fisheries

Coral reefs and their fisheries are subject to many stresses in addition to climate change (see Chapter 4). So far, events such as the 1998 mass coral bleaching in the Indian Ocean have not provided evidence of negative short-term bio-economic impacts for coastal reef fisheries (Spalding and Jarvis, 2002; Grandcourt and Cesar, 2003). In the longer term, there may be serious consequences for fisheries production that result from loss of coral communities and reduced structural complexity, which result in reduced fish species richness, local extinctions and loss of species within key functional groups of reef fish (Sano, 2004; Graham et al., 2006).

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.

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 8.4.1.2), affect labour available for agriculture and other non-farm rural economic activities, such as tourism (see Chapter 7, Section 7.4.2.2).

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

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