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7 - The land and food submodel: TERRA
- from Part One - The TARGETS model
- Edited by Jan Rotmans, National Institute of Public Health and Environment (RIVM), The Netherlands, Bert de Vries, National Institute of Public Health and Environment (RIVM), The Netherlands
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- Book:
- Perspectives on Global Change
- Published online:
- 06 July 2010
- Print publication:
- 16 October 1997, pp 135-158
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Summary
The aim of the land and food submodel is to simulate the key features of the global changes in land use and land cover that result from demand for food and the requirements of forestry. The submodel can reproduce the major historical trends in land use and land cover, food demand and supply, fertiliser use, etc. This is done, to a large extent, by employing of exogenous policy scenarios. The interaction with the other submodels, in particular CYCLES, allows the exploration of linkages between population growth, water availability and climate change on the one hand and food production on the other.
Introduction
The Earth's vegetation patterns have always changed in response to natural changes in, for example, geology, biology and climate. However, over the last few centuries human activities have made a considerable contribution to such changes. Natural ecosystems, forests, savannahs and wetlands have all been severely affected. The combination of growing populations and higher per capita food consumption has led to the gradual expansion of the land area used for food production and grazing. Increasing population density has led to forms of permanent agriculture which make more intensive use of land and this trend towards intensification is likely to continue in the decades to come. The growing demand for food may cause an imbalance between what can be produced and what is needed.
8 - The biogeochemical submodel: CYCLES
- from Part One - The TARGETS model
- Edited by Jan Rotmans, National Institute of Public Health and Environment (RIVM), The Netherlands, Bert de Vries, National Institute of Public Health and Environment (RIVM), The Netherlands
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- Book:
- Perspectives on Global Change
- Published online:
- 06 July 2010
- Print publication:
- 16 October 1997, pp 159-186
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Summary
The CYCLES submodel describes the long-term dynamics of the global biogeochemical cycles of carbon (C), nitrogen (N), phosphorus (P) and sulphur (S), their interactions and their impacts on climate change. The model analysis balances past carbon and nitrogen budgets – emphasising the importance of the N fertilisation feedback – and supports the future projections of the fate of anthropogenic emissions of both carbon and nitrogen compounds in the global environment presented in Chapter 16. This chapter focuses on the link between the global cycles of C and N and their feedbacks, providing calculations of global flows of these basic elements and their related compounds within and between the major reservoirs.
Introduction
Carbon, hydrogen and oxygen, together with the basic nutrient elements nitrogen, phosphorus and sulphur, are essential for life on Earth. The term ‘global biogeochemical cycles’ is used to describe the transport and transformation of these substances in the global environment. In recent decades detailed studies have been carried out on the global biogeochemical cycles of the basic elements, in particular carbon (C), nitrogen (N), phosphorus (P) and sulphur (S) (Bolin et al., 1979; Bolin and Cook, 1983; Schlesinger, 1991; Butcher et al., 1992; Wollast et al., 1993). Figure 8.1 depicts how anthropogenic disturbances of the global cycles of the basic elements of C, N, P and S lead to a variety of global environmental consequences.
15 - Food for the future
- from Part Two - Exploring images of the future
- Edited by Jan Rotmans, National Institute of Public Health and Environment (RIVM), The Netherlands, Bert de Vries, National Institute of Public Health and Environment (RIVM), The Netherlands
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- Book:
- Perspectives on Global Change
- Published online:
- 06 July 2010
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- 16 October 1997, pp 319-344
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Summary
In this chapter we use the TERRA submodel to explore whether malnutrition and food insecurity can be eliminated while safeguarding the productive potential and broader environmental functions of agricultural resources for future generations. This is done within the context of the three cultural perspectives. The food problem is explained not so much as a problem of production but as one of availability and distribution. The submodel simulations are, however, largely confined to aggregate food demand and supply. Costs and environmental trade-offs are assessed in both utopian and dystopian worlds to determine under what conditions the planet will be able to feed its future population. We explore perspective-based scenarios for population and GWP, the surface area available for cropping, the use of irrigation, fertilisers and other inputs, wood production, reforestation, and the effects of changes in atmospheric CO2 and temperature.
Introduction
Currently, sufficient food is produced to feed the world population, yet at the same time more than 1,000 million people cannot afford or do not have the possibility to buy enoughfood to live healthy and productive lives. More than 500 million are chronically undernourished (FAO, 1993a). Malnutrition and food insecurity are not so much related to food production but rather to the unequal distribution of available food (IFPRI, 1995). This is caused by socio-economic factors such as poverty, the political situation, deficient infrastructure and (food) trade.
3 - The TARGETS model
- from Part One - The TARGETS model
- Edited by Jan Rotmans, National Institute of Public Health and Environment (RIVM), The Netherlands, Bert de Vries, National Institute of Public Health and Environment (RIVM), The Netherlands
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- Book:
- Perspectives on Global Change
- Published online:
- 06 July 2010
- Print publication:
- 16 October 1997, pp 33-54
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Summary
When tackling a subject as complex as global change and sustainable development, it is essential to be able to ‘frame the issues’. This was one of the main reasons for developing the TARGETS model, an integrated model of the global system, consisting of metamodels of important subsystems. In this chapter we introduce TARGETS. Building on the previous chapters, we elaborate on the possibilities and limitations of integrated assessment models. Some of the key issues discussed are aggregation, model calibration and validation, and dealing with uncertainty.
Introduction
One of the main tools used in integrated assessment of global change issues is the Integrated Assessment (IA) model. This chapter introduces such an integrated model, TARGETS, which builds upon the systems approach and related concepts introduced in Chapter 2. Previous integrated modelling attempts either focused on specific aspects of global change, for instance the climate system (IPCC, 1995), or consisted merely of conceptual descriptions (Shaw et al., 1992). We have tried to go one step further, linking a series of cause-effect chains of global change. Although we realise the shortcomings in our current version of the TARGETS model, we felt there was a need to present our model to a wide audience. We first give some advantages and limitations of IA models. Next, we discuss issues of aggregation, calibration, validation and uncertainty. We proceed with a brief description of the five TARGETS submodels which coincides with the PSIR concept and the vertical integration as introduced in Chapter 2. A more detailed description of these submodels is given in Chapters 4 to 8.