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

16.4.3 Agriculture, fisheries and food security

Small islands have traditionally depended upon subsistence and cash crops for survival and economic development. While subsistence agriculture provides local food security, cash crops (such as sugar cane, bananas and forest products) are exported in order to earn foreign exchange. In Mauritius, the sugar cane industry has provided economic growth and has contributed to the diversification of the economy through linkages with tourism and other related industries (Government of Mauritius, 2002). However, exports have depended upon preferential access to major developed-country markets, which are slowly eroding. Many island states have also experienced a decrease in GDP contributions from agriculture, partly due to the drop in competitiveness of cash crops, cheaper imports from larger countries, increased costs of maintaining soil fertility, and competing uses for water resources, especially from tourism (FAO, 2004).

Local food production is vital to small islands, even those with very limited land areas. In the Pacific islands subsistence agriculture has existed for several hundred years. The ecological dependency of small island economies and societies is well recognised (ADB, 2004). A report by the FAO Commission on Genetic Resources found that some countries’ dependence on plant genetic resources ranged from 91% in Comoros, 88% in Jamaica, 85% in Seychelles to 65% in Fiji, 59% in the Bahamas and 37% in Vanuatu (Ximena, 1998).

Projected impacts of climate change include extended periods of drought and, on the other hand, loss of soil fertility and degradation as a result of increased precipitation, both of which will negatively impact on agriculture and food security. In a study of the economic and social implications of climate change and variability for selected Pacific islands, the World Bank (2000) found that in the absence of adaptation, a high island such as Viti Levu, Fiji, could experience damages of US$23 million to 52 million/yr by 2050, (equivalent to 2 to 3% of Fiji’s GDP in 1998). A group of low islands such as Tarawa, Kiribati, could face average annual damages of more than US$8 million to 16 million/yr (equivalent to 17 to 18% of Kiribati’s GDP in 1998) under the SRES A2 and B2 emissions scenarios.

Not all effects of climate change on agriculture are expected to be negative. For example, increased temperatures in high-latitude islands are likely to make conditions more suitable for agriculture and provide opportunities to enhance resilience of local food systems (see also Chapter 15, Section 15.5).

If the intensity of tropical cyclones increases, a concomitant rise in significant damage to food crops and infrastructure is likely. For example, Tropical Cyclone Ofa in 1990 turned Niue (in the Pacific) from a food-exporting country into one dependent on imports for the next two years, and Heta in 2004 had an even greater impact on agricultural production in Niue (Wade, 2005). Hurricane Ivan’s impact on Grenada (in the Caribbean) in 2004 caused losses in the agricultural sector equivalent to 10% of GDP. The two main crops, nutmeg and cocoa, both of which have long gestation periods, will not make a contribution to GDP or earn foreign exchange for the next 10 years (OECS, 2004).

Fisheries contribute significantly to GDP on many islands; consequently the socio-economic implications of the impact of climate change on fisheries are likely to be important and would exacerbate other anthropogenic stresses such as over-fishing. For example, in the Maldives, variations in tuna catches are especially significant during El Niño and La Niña years. This was shown during the El Niño years of 1972/1973, 1976, 1982/1983, 1987 and 1992/1994, when the skipjack catches decreased and yellow fin increased, whereas during La Niña years skipjack tuna catches increased, whilst catches of other tuna species decreased (MOHA, 2001). Changes in migration patterns and depth are two main factors affecting the distribution and availability of tuna during those periods, and it is expected that changes in climate would cause migratory shifts in tuna aggregations to other locations (McLean et al., 2001). Apart from the study by Lehodey et al. (2003) of potential changes in tuna fisheries, Aaheim and Sygna (2000) surveyed possible economic impacts in terms of quantities and values, and give examples of macroeconomic impacts. The two main effects of climate change on tuna fishing are likely to be a decline in the total stock and a migration of the stock eastwards, both of which will lead to changes in the catch in different countries.

In contrast to agriculture, the mobility of fish makes it difficult to estimate future changes in marine fish resources. Furthermore, since the life cycles of many species of commercially exploited fisheries range from freshwater to ocean water, land-based and coastal activities will also be likely to affect the populations of those species. Coral reefs and other coastal ecosystems which may be severely affected by climate change will also have an impact on fisheries (Graham et al., 2006).