U-turn Needed to Feed 10 Billion People Within Planetary Boundaries: Insights from a Global Model-based Assessment

Abstract:

This presentation will report on results from a comprehensive simulation study addressing the question how much food could be supplied globally while respecting four terrestrial planetary boundaries (i.e. guardrails describing maximum tolerable levels of global land-system change, biosphere degradation, freshwater use, and nitrogen leaching, with links to climate change). A main finding of the assessment is that almost half of current food production depends on transgressions of planetary boundaries and their sub-global constituents (such as deforestation, or overdraft of freshwater at the cost of rivers’ environmental flow requirements). The assessment represents the four planetary boundaries in a spatially explicit manner (partly based on revised boundary definitions and calculations). This way it is possible to reveal the magnitudes and spatial patterns of individual boundary transgressions including demonstration of where several of them might be transgressed simultaneously due to the agricultural activities.

Subsequent simulations show that the same amount of food presently produced under these unsustainable conditions, and even substantially more, could be provided without violating the (sub)planetary boundaries in any place. The prerequisites to halt, or even revert, the boundary transgressions while keeping up production levels are: more efficient use of blue and green water as well as of nutrients, reallocation of rainfed and irrigated cropland to areas where that would still be acceptable, reduction of food losses, dietary shifts towards lower shares of animal-based products, and – importantly – combinations thereof. Assuming ambitious yet feasible implementation levels of the various measures, it appears to be possible to provide enough food for around 10 billion people within the four planetary boundaries.