The food system is a major driver of climate change, land-use change, depletion of freshwater resources, and pollution of aquatic and terrestrial ecosystems by excessive nitrogen and phosphorus inputs. Here we show that as a result of expected changes in population and income levels, the environmental impacts of the food system could increase by 60-90% between 2010 and 2050 in absence of technological changes and dedicated mitigation measures, and reach levels that are beyond planetary boundaries that define a safe operating space for humanity. We analyse several options for reducing the environmental impacts of the food system, including dietary changes towards healthier, more plant-based diets, improvements in technologies and management, and reductions in food loss and waste. We find that no single measure is enough to simultaneously stay within all planetary boundaries, and combining each measure synergistically will be needed to sufficiently mitigate the projected increase in environmental pressures.

Nitrogen (N) is crucial for crop productivity. However, nowadays more than half of the N added to cropland is lost to the environment, wasting the resource, producing threats to air, water, soil and biodiversity, and generating greenhouse gas emissions. Based on FAO data, we have reconstructed the trajectory followed, in the past 50 years, by 124 countries in terms of crop yield and total nitrogen inputs to cropland (manure, synthetic fertilizer, symbiotic fixation and atmospheric deposition). During the last five decades, the response of agricultural systems to increased nitrogen fertilization has evolved differently in the different world countries. While some countries have improved their agro-environmental performances, in others the increased fertilization has produced low agronomical benefits and higher environmental losses. Our data also suggest that, in general, those countries using a higher proportion of N inputs from symbiotic N fixation rather than from synthetic fertilizer have a better N use efficiency.

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