Assumptions about future trends in climate food forestry and fisheries

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Declining global population growth (UN, 2004), rapidly rising urbanisation, shrinking shares of agriculture in the overall formation of incomes and fewer people dependent on agriculture are among the key factors likely to shape the social setting in which climate change is likely to evolve. These factors will determine how climate change affects agriculture, how rural populations can cope with changing climate conditions, and how these will affect food security. Any assessment of climate change impacts on agro-ecological conditions of agriculture must be undertaken against this background of changing socio-economic setting (Bruinsma, 2003).

5.3.1 Climate

Water balance and weather extremes are key to many agricultural and forestry impacts. Decreases in precipitation are predicted by more than 90% of climate model simulations by the end of the 21st century for the northern and southern sub-tropics (IPCC, 2007a). Increases in precipitation extremes are also very likely in the major agricultural production areas in Southern and Eastern Asia, in East Australia and in Northern Europe (Christensen et al., 2007). It should be noted that climate change impact models for food, feed and fibre do not yet include these recent findings on projected patterns of change in precipitation.

The current climate, soil and terrain suitability for a range of rain-fed crops and pasture types has been estimated by Fischer et al. (2002b) (see Figure 5.1a). Globally, some 3.6 billion ha (about 27% of the Earth's land surface) are too dry for rain-fed agriculture. Considering water availability, only about 1.8% of these dry zones are suitable for producing cereal crops under irrigation (Fischer et al., 2002b).

Changes in annual mean runoff are indicative of the mean water availability for vegetation. Projected changes between now and 2100 (see Chapter 3) show some consistent runoff patterns: increases in high latitudes and the wet tropics, and decreases in mid-latitudes and some parts of the dry tropics (Figure 5.1b). Declines in water availability are therefore projected to affect some of the areas currently suitable for rain-fed crops (e.g., in the Mediterranean basin, Central America and sub-tropical regions of Africa and Australia). Extreme increases in precipitation

Impact This Current Rain
Figure 5.1. (a) Current suitability for rain-fed crops (excluding forest ecosystems) (after Fischer et al., 2002b). SI = suitability index; (b) Ensemble mean percentage change of annual mean runoff between present (1981 to 2000) and 2100 (Nohara et al., 2006).

(Christensen et al., 2007) also are very likely in major agricultural production areas (e.g., in Southern and Eastern Asia and in Northern Europe).

5.3.2 Balancing future global supply and demand in agriculture, forestry and fisheries

53.2.1 Agriculture

Slower population growth and an increasing proportion of better-fed people who require fewer additional calories are projected to lead to deceleration of global food demand. This slow-down in demand takes the present shift in global food consumption patterns from crop-based to livestock-based diets into account (Schmidhuber and Shetty, 2005). In parallel with the slow-down in demand, FAO (FAO, 2005a) expects growth in world agricultural production to decline from 2.2%/yr during the past 30 years to 1.6%/yr in 2000 to 2015,1.3%/yr in 2015 to 2030 and 0.8%/yr in 2030 to 2050. This still implies a 55% increase in global crop production by 2030 and an 80% increase to 2050 (compared with 1999 to 2001). To facilitate this growth in output, another 185 million ha of rain-fed crop land (+19%) and another 60 million ha of irrigated land (+30%) will have to be brought into production. Essentially, the entire agricultural land expansion will take place in developing countries with most of it occurring in sub-Saharan Africa and Latin America, which could result in direct trade-offs with ecosystem services (Cassman et al., 2003). In addition to expanded land use, yields are expected to rise. Cereal yields in developing countries are projected to increase from 2.7 tonnes/ha currently to 3.8 tonnes/ha in 2050 (FAO, 2005a).

These improvements in the global supply-demand balance will be accompanied by a decline in the number of undernourished people from more than 800 million at present to about 300 million, or 4% of the population in developing countries, by 2050 (see Table 5.6) (FAO, 2005a). Notwithstanding these overall improvements, important food-security problems remain to be addressed at the local and national levels. Areas in sub-Saharan Africa, Asia and Latin America, with high rates of population growth and natural resource degradation, are likely to continue to have high rates of poverty and food insecurity (Alexandratos, 2005). Cassman et al. (2003) emphasise that climate change will add to the dual challenge of meeting food (cereal) demand while at the same time protecting natural resources and improving environmental quality in these regions.

5.3.22 Forestry

A number of long-term studies on supply and demand of forestry products have been conducted in recent years (e.g., Sedjo and Lyon, 1990,1996; FAO, 1998; Hagler, 1998; Sohngen et al., 1999,2001). These studies project a shift in harvest from natural forests to plantations. For example, Hagler (1998) suggested the industrial wood harvest produced on plantations will increase from 20% of the total harvest in 2000 to more than 40% in 2030. Other estimates (FAO, 2004a) state that plantations produced about 34% of the total in 2001 and predict this portion may increase to 44% by 2020 (Carle et al., 2002) and 75% by 2050 (Sohngen et al., 2001). There will also be a global shift in the industrial wood supply from temperate to tropical zones and from the Northern to Southern Hemisphere. Trade in forest products will increase to balance the regional imbalances in demand and supply (Hagler, 1998).

Forecasts of industrial wood demand have tended to be consistently higher than actual demand (Sedjo and Lyon, 1990). Actual increases in demand have been relatively small (compare current demand of 1.6 billion m3 with 1.5 billion m3 in the early 1980s (FAO, 1982,1986,1988,2005b)).The recent projections of the FAO (1997), Haggblom (2004), Sedjo and Lyon (1996) and Sohngen et al. (2001) forecast similar modest increases in demand to 1.8-1.9 billion m3 by 2010 to 2015, in contrast to earlier higher predictions of 2.1 billion m3 by 2015 and 2.7 billion m3 by 2030 (Hagler, 1998). Similarly, an FAO (2001) study suggests that global fuelwood use has peaked at 1.9 billion m3 and is stable or declining, but the use of charcoal continues to rise (e.g., Arnold et al., 2003). However, fuelwood use could dramatically increase in the face of rising energy prices, particularly if incentives are created to shift away from fossil fuels and towards biofuels. Many other products and services depend on forest resources; however, there are no satisfactory estimates of the future global demand for these products and services.

Finally, although climate change will impact the availability of forest resources, the anthropogenic impact, particularly land-use change and deforestation in tropical zones, is likely to be extremely important (Zhao et al., 2005). In the Amazon basin, deforestation and increased forest fragmentation may impact water availability, triggering more severe droughts. Droughts combined with deforestation increase fire danger (Laurance and Williamson, 2001): simulations show that during the 2001 ENSO period approximately one-third of Amazon forests became susceptible to fire (Nepstad et al., 2004).

532.3 Fisheries

Global fish production for food is forecast to increase from now to 2020, but not as rapidly as world demand. Per capita fish consumption and fish prices are expected to rise, with wide variations in commodity type and region. By 2020, wild-capture fisheries are predicted to continue to supply most of the fish produced in sub-Saharan Africa (98%), the USA (84%) and Latin America (84%), but not in India (45%) where aquaculture production will dominate (Delgado et al., 2003). All countries in Asia are likely to produce more fish between 2005 and 2020, but the rate of increase will taper. Trends in capture fisheries (usually zero growth or modest declines) will not unduly endanger overall fish supplies; however, any decline of fisheries is cause for concern given the projected growth in demand (Briones et al., 2004).

532.4 Subsistence and smallholder agriculture

'Subsistence and smallholder agriculture' is used here to describe rural producers, predominantly in developing countries, who farm using mainly family labour and for whom the farm provides the principal source of income (Cornish, 1998). Pastoralists and people dependent on artisanal fisheries and household aquaculture enterprises (Allison and Ellis, 2001) are also included in this category.

There are few informed estimates of world or regional population in these categories (Lipton, 2004). While not all smallholders, even in developing countries, are poor, 75% of the world's 1.2 billion poor (defined as consuming less than one purchasing power-adjusted dollar per day) live and work in rural areas (IFAD, 2001). They suffer, in varying degrees, problems associated both with subsistence production (isolated and marginal location, small farm size, informal land tenure and low levels of technology), and with uneven and unpredictable exposure to world markets. These systems have been characterised as 'complex, diverse and risk-prone' (Chambers et al., 1989). Risks (Scoones et al., 1996) are also diverse (drought and flood, crop and animal diseases, and market shocks) and may be felt by individual households or entire communities. Smallholder and subsistence farmers and pastoralists often also practice hunting-gathering of wild resources to fulfil energy, clothing and health needs, as well as for direct food requirements. They participate in off-farm and/or non-farm employment (Ellis, 2000).

Subsistence and smallholder livelihood systems currently experience a number of interlocking stressors other than climate change and climate variability (outlined in Section 5.2.2). They also possess certain important resilience factors: efficiencies associated with the use of family labour (Lipton, 2004), livelihood diversity that allows the spreading of risks (Ellis, 2000) and indigenous knowledge that allows exploitation of risky environmental niches and coping with crises (see Cross Chapter Case Study on Indigenous Knowledge). The combinations of stressors and resilience factors give rise to complex positive and negative trends in livelihoods. Rural to urban migration will continue to be important, with urban populations expected to overtake rural populations in less developed regions by 2017 (UNDESA 2004). Within rural areas there will be continued diversification away from agriculture (Bryceson et al., 2000); already non-farm activities account for 30-50% of rural income in developing countries (Davis, 2004). Although Vorley (2002), Hazell (2004) and Lipton (2004) see the possibility, given appropriate policies, of pro-poor growth based on the efficiency and employment generation associated with family farms, it is overall likely that smallholder and subsistence households will decline in numbers, as they are pulled or pushed into other livelihoods, with those that remain suffering increased vulnerability and increased poverty.

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