gtap

The actual land use consequences of crop consumption are not very well reflected in existing life cycle inventories. The state of the art is that such inventories typically include data from crop production in the country in which the crop is produced, and consequently the inventories do not necessarily consider the land ultimately affected in the systems being studied. The aims of this study are to analyse the mechanisms influencing the long-term land use consequences of changes in crop demand and to propose a methodological framework for identifying these consequences within a global scope. The study refers to the principles of consequential LCA, which means that the consequences of changes in consumption are studied from a market-based perspective. In this context, the study addresses the feasibility of using economic modelling to identify ultimate land use consequences of crop consumption. Based on the current market trend for crops and an analysis of basic mechanisms in crop production, concepts for modelling how crop consumption affects the global agricultural area and the intensity of crop production are suggested. It is demonstrated how the assumptions concerning drivers for technological development have a profound influence on identification of the marginal response to crop consumption, and how the geographical location of crop consumption also influences the composition of the marginal production response in terms of cropland expansion and intensification. Crop prices have been falling at a global scale and are projected to decline further. At the same time, crop yields per hectare are continuously increasing. This indicates that drivers other than crop demand have a strong influence on technological development in crop production.Economic modelling in combination with geographical information and agricultural statistics can be used to estimate long-term land use consequences of changes in crop consumption. The GTAP Model is a suitable tool although it requires implementation of land supply curves, adjustment of elasticities to reflect long-term changes, and possibly establishment of a link between crop demand and technological development. Through this approach, life cycle inventories for crops reflecting the actual land use consequences of consumption can be established. Further work (based on the methodological framework in this study) will address the practical modelling of land use changes induced by crop consumption in different regions with the purpose of including this in LCI.

This paper offers a graphical exposition of the GTAP model of global trade. Particular emphasis is placed on the accounting, or equilibrium, relationships in the model. It begins with a treatment of the a one region version of GTAP, thereafter adding a rest of world region to highlight the treatment of trade flows in the model. The implementation of policy instruments in GTAP is also explored, using simple supply-demand graphics. The material provided in this paper was first developed as an introduction to GTAP for participants taking the annual short course. Based on its success in that venue, this paper has been placed on the ?highly recommended? reading list for individuals seeking an introduction and overview of the GTAP framework. It was modified in March of 2001 to reflect the changes in version 6.0 of the GTAP model.

The preceding two chapters of this volume have discussed physical and economic data bases for global agriculture and forestry, respectively. These form the foundation for the integrated, global land use data base discussed in this chapter. However, in order to utilize these data for global CGE analysis, it is first necessary to integrate them into a global, general equilibrium data base. This integration is the subject of the present chapter

In recent years, considerable concern has been raised about the sustainability of the world's forested ecosystems (FAO, 2003). With deforestation rates in tropical regions estimated to be as high as 12 million hectares per year (FAO, 2003; Houghton, 2003), much of the concern has centered around tropical deforestation. In contrast to these developments in tropical areas, there is evidence that the area of forests in temperate regions is expanding. Given the large potential storage of carbon in both temperate and tropical forests, these changes in land use can potentially lead to large fluxes of carbon both into and out of forests (Houghton, 2003; Plattner et al. 2002; Dixon et al., 1994). In addition to the potential carbon fluxes, forest management and land use change influences a host of other local and global environmental impacts.

The Center for Sustainability and the Global Environment (SAGE) at the University of Wisconsin has been developing global databases of contemporary and historical agricultural land use and land cover. SAGE has chosen to focus on agriculture because it is clearly the predominant land use activity on the planet today, and provides a vital service?i.e., food?for human societies. SAGE has developed a ?data fusion? technique to integrate remotely-sensed data on the world?s land cover with administrative-unit-level inventory data on land use (Ramankutty and Foley, 1998; Ramankutty and Foley, 1999; Ramankutty et al., in press). The advent of remote sensing data has been revolutionary in providing consistent, global, estimates of the patterns of global land cover. However, remote sensing data are limited in their ability to resolve the details of agricultural land cover from space. Therein lies the strength of the ground-based inventory data, which provide detailed estimates of agricultural land use practices. However, inventory data are limited in not being spatially explicit, and these data are also plagued by problems of inconsistency across administrative units. The ?data fusion? technique developed by SAGE exploits the strengths of both the remotely-sensed data as well as the inventory data.

The paper describes the on-going project of the GTAP land use data base. We also present the GTAPE-AEZ model, which illustrates how land use and land-based emissions can be incorporated in the CGE framework for Integrated Assessment (IA) of climate change policies. We follow the FAO fashion of agro-ecological zoning (FAO, 2000; Fischer et al, 2002) to identify lands located in six zones. Lands located in a specific AEZ have similar (or homogenous) soil, landform and climatic characteristics. The six AEZs range over a spectrum of length of growing period (LGP) for which their climate characteristics can support for crop growing. AEZ 1 covers the land of the temperature and moisture regime that is able to support length of growing period (LGP) up to 60 days per annum. On the other end of the LGP spectrum, lands in AEZ 6 can support a LGP from 270 to 360 days per annum. Crop growing, livestock breeding, and timber plantation are dispersed on lands of each AEZ of the six, whichever meets their climatic and edaphic requirements. In GTAPE-AEZ, we assume that land located in a specific AEZ can be moved only between sectors that the land is appropriate for their use. That is, land is mobile between crop, livestock and forestry sectors within, but not across, AEZ’s. In the