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Human-directed impacts on food and land-based ecosystems and their implications for food security
2.1 Multiple drivers of land use change: mixed effects on food security
The clear depiction of climate impact on land as a result of human-directed forces is important in terms of food security policy. It also calls for action to achieve mitigation targets, as well as adaptation and resilience objectives.
The human-directed forces of land use and its changes are multiple. These range from population growth and migration, to livelihoods (e.g. income, poverty), access to resources (e.g. land tenure, traditional rights to resource use), market forces (e.g. expansion of commercial agriculture, trade, usage, natural market developments, migration), technologies (e.g. genetic, mechanical), to income-induced alterations in food preferences and diets and economic drivers.
There are important and often complex interactions between many of these drivers whose ramifications are diverse, with sometimes unexpected outcomes in terms of land use and food security. The pressure on land in a country of outmigration, for example, may not be lessened as a result of the migrants’ demands for food and rising incomes in a host country. As a result of their rising income, food demand from home countries increases both through trade (with the host country) and higher incomes for households receiving remittances. In fact, the outmigration country may experience a rise in food production and/or food exports. This example illustrates the necessity to adopt a land systems perspective that fully acknowledges the inherent trade-offs and is not tied to a single-indicator perspective, which by itself may not achieve sustainability.
Forest transition (i.e. reversal of agricultural land to forests) is determined by several converging factors. Viet Nam, for example, has reduced deforestation in its highlands through a combination of labour outmigration to more productive and profitable neighbouring rice areas and has provided government support for reforestation.7 In China urbanization, combined with declining crop profitability, has caused farm outmigration in parallel with an enabling environment from the government to reverse cropland forests. The outmigration in India and Nepal from agriculture, together with a structural change in the economy over the past 10−15 years in terms of government subsidies, have opened new agricultural lands for reforestation.
In arid and semi-arid regions, land use change can arise from a direct production decline and at times lead to desertification. The indirect impact of land use changes is mediated through carbon stock loss, lower water and nutrient cycling and habitat loss. The socio-economic indirect impacts include a rise in food and nutrition insecurity, lower income and increased poverty. A recent study estimated the annual cost of land use changes, in terms of loss of environmental ecosystem services, at around US$230 billion annually.8 In dry lands, net crop productivity loss has been recorded at between 10 and 30 percent in many areas, especially in parts of Africa, and in Australia, Central Asia, Latin America and the United States as a result of dry land degradation.
Given that a good portion of resource loss from human-directed drivers of land use change is not accounted for in
the marketplace, land degradation will continue. In terms of regional impact, Africa loses the most, with estimates putting the annual deficit at 7 percent of gross domestic product, largely because of the loss of forests with high value biomes. Since markets fully internalize these costs (externalities), corrective action of any significance would require a combination of government policy and regulation, complemented with market instruments where appropriate.
In terms of food security, the impact of land use change is mixed not only with opportunities for synergies but also trade-offs. While cropland expansion can increase food production in the short run (e.g. from deforestation), it may come at a high biodiversity cost and ecosystem loss if the crops replace high value biomes (e.g. tropical forests or mangroves). While the potential to help for agricultural intensification is real, it may contribute to deforestation, a fact that is widely acknowledged.9 Expansion of urbanization comes at the expense of cropland, with estimates of about
4 percent food production loss to urbanization annually by 2030.10 Nevertheless, urbanization may offer a higher alternative income which improves access to food.
Meyfroidt and Lambin. (2008). Nyonka et al. (2016).
Byerlee et al. (2014).
10 D’Amour et al. (2016).
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FAO-IPCC Expert meeting on climate change, land use and food security