IMPACTS ON ENVIRONMENTAL DEGRADATION ON YIELD AND AREA

The natural environment, with all its ecosystem services, comprises the entire basis for life on the planet. Its value is therefore impossible to quantify or even model. The state of environment has – at any given stage – effects on food production through its role in water, nutrients, soils, climate and weather as well as on insects that are important for pollination and regulating infestations. The state of ecosystems also influences the abundance of pathogens, weeds and pests, all factors with a direct bearing on the quality of available cropland, yields and harvests.

Environmental degradation due to unsustainable human practices and activities now seriously endangers the entire production platform of the planet.

Land degradation and conversion of cropland for non-food production including biofuels, cotton and others are major threats that could reduce the available cropland by 8–20% by 2050. Species infestations of pathogens, weeds and insects, combined with water scarcity from overuse and the melting of the Himalayas glaciers, soil erosion and depletion as well as climate change may reduce current yields by at least an additional 5–25% by 2050, in the absence of policy intervention. These factors entail only a portion of the environment covering direct effects. The indirect effects, including socio-economic responses, may be considerably larger.

THE ROLE OF THE ENVIRONMENT IN FOOD PRODUCTION

There is a strong link between the state of the environment and food production, apart from the natural environment being the entire platform upon which all life is based. For crops, the state of the environment directly influences soil nutrient availability, water (ground and surface water for irrigation), climate and weather (rainfall and growth season), availability of insects for pollination, and not the least, the abundance and effects of certain pests, such as pathogens, insects and weeds, which have major impact on crops worldwide, particularly in Africa (Sanchez, 2002). Without these services, there would be no production, Ecosystem services enhance agro-ecosystem resilience and sustain agricultural productivity. Thus, promoting the healthy functioning of ecosystems ensures the sustainability of agriculture as it intensifies to meet the growing demands for food production.

The interaction among these variables is very complex, and providing quantitative estimates of their significance is nearly impossible. The key variables are not currently accounted for in most models and scenarios of food production (FAO, 2003; 2006). 

In this chapter we attempt to provide estimates of possible ranges of future impacts of environmental degradation on yield and available cropland, based on the best knowledge available, peer-reviewed studies and expert judgment. We will not, however, attempt to quantify the full value of ecosystem services from the environment, which entail complex interactions and processes. The estimates given here are of possible ranges based on some current projections of the degree of environmental degradation. 

The FAO has provided estimates of cropland and yield increases necessary to meet future demand for food, without fully considering the role of environmental degradation and losses of ecosystem services. Hence, the following material provides an insight into the possible losses (and the compensation needed) in food production as a result of environmental degradation, to support other UN agencies in further improving estimates of demand and production in a changing world.

LOSS OF CROPLAND AREA

There has been a growing trend all over the world in converting cropland to other uses due to increasing urbanization, industrialization, energy demand and population growth. China, for example, lost more than 14.5 million ha of arable land between 1979 and 1995 (ICIMOD, 2008). 

Current projections suggest that an additional 120 million ha –  an area twice the size of France or one-third that of India – will be needed to support the traditional growth in food production by 2030, mainly in developing countries (FAO, 2003), without considering the compensation required for certain losses. The demand for irrigated land is projected to increase by 56% in Sub-Saharan Africa (from 4.5 to 7 million ha), and rainfed land by 40% (from 150 to 210 million ha) in order to meet the demand, without considering ecosystem services losses and setbacks in yields and available cropland (FAO, 2003; 2006). Increases in available cropland may be possible in Latin America through the conversion of rainforests (Figure 13), which in turn will accelerate climate change and biodiversity losses, causing feedback loops that may hinder the projected increases in crop yields. The potential for increases is more questionable in large parts of sub-Saharan Africa due to political, socio-economic and environmental constraints. In Asia, nearly 95% of the potential cropland has already been utilized (FAO, 2003; 2006).  Even if such increases are not restricted by other land use and the protection of tropical rainforests, changes in the proportion of non-food crops to food crops may have even greater impacts on the available cropland for food production.

Figure 13: Theoretical potential for cropland expansion, irrespective of conservation, water and other environmental issues. (Source: FAO, 2003).

BIOFUELS AND COTTON – SUSTAINABLE OPTIONS TO INCREASE INCOMES OR THREAT TO BIODIVERSITY AND FOOD PRODUCTION?

Biofuels have grown quickly in demand and production (Figure 14), fuelled by high oil prices and the initial perception of their role in reducing CO2 emissions (FAO, 2008). Biofuels, including biodiesel from palm oil and ethanol from sugarcane, corn and soybean, accounted for about 1% of the total road transport in 2005, and may reach 25% by 2050, with the EU having set targets as high as 10% by 2020 (World Bank, 2007; FAO, 2008). For many countries, such as Indonesia and Malaysia, biofuels are also seen as an opportunity to improve rural livelihoods and boost the economy through exports (Fitzherbert et al., 2008; UNEP, 2008). The US is the largest producer and consumer of bioethanol, followed by Brazil (Figure 15) (World Bank, 2007; FAO, 2008). Brazil has now used 2.7 million ha of land area for this production (4.5% of the cropland area), mainly sugar cane.

While biofuels are a potential low-carbon energy source, the conversion of rainforests, peatlands, savannas, or grasslands to produce biofuels in the US, Brazil and Southeast Asia may create a “biofuel carbon debt” by releasing 17 to 420 times more CO2 than the annual greenhouse gas reductions that these biofuels would provide by displacing fossil fuels (Fargione et al., 2008; Searchinger et al., 2008). Corn-based ethanol, instead of producing a 20% savings, will nearly double greenhouse emissions over 30 years (Searchinger et al., 2008). Biofuels from switchgrass, if grown on US corn lands, will increase emissions by 50% (Fargione et al., 2008). It is evident that the main potential of biofuels lies in using waste biomass or biomass grown on degraded and abandoned agricultural lands planted with perennials (World Bank, 2007; FAO, 2008). 

 
Figure 14: The production of biodiesel and ethanol has increased substantially in recent years. (Source: Earth Policy Institute, 2006). Figure 15: United States and Brazil are among the greatest producers of biofuels today. (Source: Earth Policy Institute, 2006).

Production of crops for biofuels also competes with food production (Banse et al., 2008). Indeed, the corn equivalent of the energy used on a few minutes drive could feed a person for a day, while a full tank of ethanol in a large 4-wheel drive suburban utility vehicle could almost feed one person for a year. A recent OECD-FAO (2007) report expected food prices to rise by between 20% and 50% by 2016 partly as a result of biofuels. Already, drastically raised food prices have resulted in violent demonstrations and protests around the world in early 2008. Current OECD scenarios by the IMAGE model project a mean increase in the proportion of land allocated to crops for biofuel production equivalent to 0.5% of the cropland area in 2008, 2% by 2030 (range 1–3%) and 5% by 2050 (range 2–8%).

Production of other non-food crops is also projected to increase. For example, cotton is projected to increase to an additional 2% of cropland area by 2030 and 3% by 2050 (Ethridge et al., 2006; FAPRI 2008). Hence, the combined increase in cropland area designated for the production of biofuels and cotton alone could be in the range of 5–13% by 2050 and have the potential to negatively impact food production and biodiversity.

LOSS OF CROPLAND FROM URBAN DEVELOPMENT

Infrastructure and urban development is increasing rapidly (UN, 2008). Settlement primarily occurred at the cost of cropland, as people historically settled in the most productive locations (e.g., Maizel et al. 1998; Goldewijk, 2001, 2005; Klein Goldewijk and Beusen, 2009). Hence, as settlements, towns and cities grow, the adjacent cropland is reduced to accommodate urban infrastructure such as roads and housing. Globally, estimates of the extent of built-up areas in 2000 range from 0.2% – 2.7% of the total land area (Potere and Schneider, 2007) with 5 of the 7 estimates below 0.5%. Most of the differences can be explained by the various definitions of built-up area and differences between satellite derived and inventory based data. All these percentages relate to about 0.3–3.5 million km2 of land worldwide, which at first appear to be unavailable for producing food. However, UNDP (1996) estimated that 15– 20% of the world’s food is produced in (peri-)urban areas (although it is not clear whether parts of this peri-urban area are already included in cropland inventories or not; besides there is large uncertainty and variability by city/region of the UNDP estimate).

Preliminary future estimates based on the HYDE methodology (Beusen and Klein Goldewijk, in prep) with the medium population growth variant of the UN (2008) reveal that with an expected increase of the global urban population from 2.9 billion people in 2000 to 5 billion in 2030 and 6.4 billion in 2050, the built-up area is likely to increase from 0.4% of the total global land area in 2000 to about 0.7% by 2030, and to 0.9% by 2050, corresponding roughly to 0.5 million km2, 0.9 million km2 and 1.2 million km2, respectively.

The computed ratio of built-up area/cropland area is 3.5% in 2000, 5.1% in 2030 and 7% in 2050, respectively. This means that if all additional built-up area would be at the expense of cropland (Stehfest et al., 2008), a total of 0.37 million km2 of cropland would be lost by 2030, and another 0.30 million km2 by 2050.

LOSS OF CROPLAND AREA FROM LAND DEGRADATION

About 2 billion ha of the world’s agricultural land have been degraded because of deforestation and inappropriate agricultural practices (Pinstrup-Andersen and Pandya-Lorch, 1998). In spite of global improvements on some parts of the land, unsustainable land use practices result in net losses of cropland productivity – an average of 0.2%/year. The combined effects of competition for land from growing populations, reduced opportunity for migration and rotation along with higher livestock densities, result in frequent overgrazing and, hence, loss of long-term productivity. Satellite measurements show that between 1981 and 2003, there was an absolute decline in the productive land area (as Net Primary Productivity) across 12% of the global land area. The areas affected are home to about 1–1.5 billion people, some 15–20% of the global population (Bai et al., 2007).

A number of authors including den Biggelaar et al. (2004) estimate that globally, 20,000–50,000 km2 of land are lost annually through land degradation, chiefly soil erosion, with losses 2–6 times higher in Africa, Latin America and Asia than in North America and Europe. The major degrading areas are in Africa south of the Equator, Southeast Asia, Southern China, North-Central Australia and the pampas of South America. Some 950,000 km2 of land in Sub-Saharan Africa is threatened with irreversible degradation if nutrient depletion continues (Henao and Baanante, 2006). In most parts of Asia, forest is shrinking, agriculture is gradually expanding to marginal lands and land degradation is accelerating through nutrient leaching and soil erosion. In fact, about 20% of the agricultural land in Asia has been degraded over the last several decades (Foley et al., 2005). The pace of degradation is much higher in environmentally fragile areas, such as on the mountains.

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