Drivers of global land use change : are increasing demands for food and bioenergy offset by technological change and yield increase?

Sammanfattning: Globally, the food and energy demands of the growing global population are rising and require increased agricultural production. Additionally, climate change will have adverse effects on agricultural productivity. Technological change can contribute to closing yield gaps and reducing post-harvest losses, but needs to be facilitated through investments and education. Considering the multiple drivers of the land system and their complex interactions, it is one of the great challenges of the 21st century to find solutions for how to sustainably increase food and bioenergy production. This requires understanding of land use change, its drivers and their multiple interactions. Here, a parsimonious land use model (PLUM) is developed and a review of global scenarios of environmental change is carried out to address the question of how drivers of environmental change, including lifestyle-related dietary changes, bioenergy production, and technological change, will affect future land use. The results of the model development and evaluation suggest that a parsimonious approach can contribute to understanding and exploring solutions to the challenge outlined above. The model can reproduce agricultural land use at the global and regional scale and at the same time the approach is explicit about uncertainties in model input parameters and the quantification of uncertainty ranges for each model output. The exploration of the uncertainty range of the model parameters showed that global cereal land is strongly affected by changes in cereal yields in developing countries. The increasing demand for food, represented by cereals, milk and meat, had in the past 20 years only very little influence on expanding agricultural land. The results of the review of bioenergy representation in global scenario studies show that assumptions related to technological change, such as yield increase and efficiency of bioenergy production, are essential for the projected land use for bioenergy in the future. The projected land use for bioenergy in the reviewed scenarios spans 0.2-10% of total global area in 2100, which can be considered a wide range, given that current cropland is about 12% of global land area. Further, the research suggests that high primary energy requirements, mitigation strategies, or a combination of these driving forces, will in any case stimulate an increased bioenergy production in the future.

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