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Human societies in advanced economies and increasingly those in emerging economies, are consuming more resources than the planet can regenerate, and filling waste sinks at a more rapid rate than the planet can assimilate (Princen, 1999). Anthropocentric climate change represents the most obvious and critical example of this, as the capacity of the atmosphere and biosphere for adsorption of additional greenhouse gas (GHG) emissions has currently been exceeded (van den Bergh, 2010)1. However, global CO2 emissions, the most significant anthropogenic GHG, are projected to continue to rise in the period to 2035. Because of these and existing levels of emissions, the global mean surface temperature change for the period 2016–2035 (relative to 1986–2005) is predicted to be in the range of 0.3°C to 0.7°C (IPCC, 2013). These are emissions levels that carry very high risks of major economic, social and biophysical damage to the planet (Sheehan et al., 2008). Against this background, the demand for food is forecast to grow by at least 50% over the next four decades, driven by population growth and rising affluence in many of the Earth’s fastest growing regions (Food Policy Editorial, 2011). In addition, forecasts from petroleum geology models of post-peak oil production indicate supply declines from 1.5% to 6% per year (Krumdieck, S., Page, S., & Dantas, 2010). Harvey and Pilgrim (2011) and Tilman et al. (2009) refer to the ‘trilemma challenge’ posed by these interconnected problems, whereby land availability, energy, and climate change each pose critical problems for the sustainable development of world economies, and measures to address one component of the trilemma, may adversely affect another. The ‘trilemma’ will both increase the cost of energy for agri-food systems and perhaps more significantly increase the demand for land to grow energy crops For instance, the use of bio-fuels in place of fossil fuels increasingly represents a strategy to reduce climate emissions and increase energy security. However, adverse impacts also include the appropriation of valuable arable land, as well as ecological impacts at the local scale. In this regard, the sustainability of agri-food systems is at the core of sustainable development challenges of the 21st century.
Presently, the agri-food system appropriates a significant proportion of global resources, including over 30% of all ice-free land, 70% of available freshwater and 20% of energy (Aiking, 2011). During the 21st century, resources such as land, labour, energy and agrochemicals are predicted to become scarcer and as a result, more expensive (Fresco, 2009; Harvey & Pilgrim, 2011). While a sustainable system of food production for 2.3 billion more people in the next four decades requires societal transition and industrial transformation (Aiking, 2011), key trends appear to be moving contrary to this. The shift in demand from local and seasonal toward imported, non-seasonal fruit and vegetables increases transportation, cooling, and freezing inputs, with a corresponding increase in energy use, for example (Rayner, Barling, & Lang, 2008).