Food system and planetary boundaries.

How can we envisage cohabitation between humans and the rest of biodiversity, between humans and ‘non humans,’ in our shared ‘critical zone,’ that thin layer of life on the Earth’s surface whose equilibrium is under threat? This challenge is exacerbated by the environmental changes already underway, of which climate disruption is only one dimension. Will agriculture have to increase its production by a quarter to feed 25% more people, while remaining one of the main sources of greenhouse gas emissions, deforestation, and soil and water degradation? Will the intensification of livestock farming and extensive monocultures increase the pressure on ecosystems and lead to an irremediable loss of biodiversity? 

The scientific community has long demonstrated the need for a complex transition to agriculture that is not only sustainable but also regenerative. This means adopting practices such as agroecology, agroforestry, and integrated crop management to restore soil health, improve agricultural resilience, and reduce dependence on inputs. In addition, land tenure reform must go hand in hand with equitable redistribution of agricultural resources. Robust forms of local and global governance are also needed to support these transitions and improve the social, economic and health protection of workers in the food system. Ambitious policies, investment in agronomic, economic, and social research, and international cooperation are essential to promote sustainable agriculture and fisheries on a global scale.

The cycle of nitrogen, an essential nutrient for cultivated plants

Nitrogen (N) is essential for plant growth. However, the environmental impact of the nitrogen derivatives present in fertilisers in the form of nitrates, as well as in cattle and pig manure, is profound and multi-faceted. Excess nitrogen from fertilisers and manure leaches into groundwater and contaminates drinking water supplies, causing serious health problems. Nitrogen run-off into rivers, lakes, and coastal waters leads to their ‘eutrophication,’ the proliferation of harmful algae that deplete oxygen and kill aquatic life. Nitrogen compounds also partly volatilize into the atmosphere in the form of ammonia and nitrous oxide (N₂O), contributing to air pollution and exacerbating climate change through their role as powerful greenhouse gases. These problems underline the urgent need to improve the management of the nitrogen cycle in agriculture in order to protect the environment and human health.

The phosphorus and potassium cycles

Used as fertilisers in agriculture, phosphorus (P) and potassium (K) improve the yield of the crops that ‘feed’ on them but damage the environment. They come mainly from mining and the evaporation of salt water, which is the first form of environmental damage. If they are not fully assimilated by plants, these ‘inputs,’ once applied, cause major pollution, particularly in aquatic cycles. Run-off water from crop fields carries these elements to rivers, lakes, seas, and oceans, contributing to ‘eutrophication’: a proliferation of algae that depletes oxygen in the water and threatens aquatic life. Excessive use of these fertilisers also leads to an imbalance of nutrients in the soil, compromising biodiversity and the sustainability of farmland sooner or later. Controlling the phosphorus and potassium cycles on a global scale is therefore essential.

Livestock, methane, and climate change

Global agricultural production, particularly intensive livestock farming for meat, has become one of the main sources of methane (CH₄) emissions over the past two centuries. Methane is primarily produced by the digestion of ruminants such as cows, sheep, and goats, as well as by the management of animal waste on farms. Methane is approximately 25 times more effective than carbon dioxide (CO₂) at trapping heat in the atmosphere over a hundred-year period. Although CO₂ is more abundant and persists longer in the atmosphere, the global warming potential of methane is much higher in the short term. Therefore, reducing methane emissions from livestock is crucial for mitigating the impact of climate change in the short term, while also reducing CO₂ emissions from other industrial and agricultural activities for a longer-term impact.

Agricultural production, carbon dioxide, and climate change

Agriculture has been one of the main sources of carbon dioxide (CO₂) emissions for several centuries. The intensive use of diesel-powered agricultural machinery is one cause. Four centuries of deforestation for the expansion of agricultural land is another. Less known are the effects of deep plowing of millions of hectares cleared since the industrial era for agriculture. Like deforestation, this has released the carbon contained in the biomass in the soil. It is also important to mention the massive production of chemical inputs such as fertilizers and pesticides, which rely on fossil fuels. However, if the regeneration of land as a carbon sink and a support for biodiversity were prioritized over short-term profit, agriculture and its techniques could become essential allies in environmental efforts, while ensuring global food security.

Overfishing and loss of marine biodiversity

The volume of fishing in the oceans has exploded since the 19th century, leading to a concerning decline in marine biodiversity. Many species are now extinct or threatened with extinction. Fishing methods have become excessive in relation to resources, particularly deep-sea fishing with ‘pelagic trawls’ and ‘drift nets,’ the use of fish aggregation devices, and the pumping of krill. The anchovy is currently the most fished species in the world. It is primarily used to produce meal intended for feeding poultry, pigs, and farmed fish. Over 80% of the fish meal produced today is used for aquaculture. Climate change exacerbates this already critical situation by warming the oceans, acidifying them due to increased CO₂ levels in the water, and decreasing their salinity due to melting ice, further jeopardizing the survival of marine species.

The loss of global biodiversity

Agricultural production has significantly contributed to the drastic reduction of biodiversity observed on a global scale. The intensive use of herbicides, insecticides, and fungicides has contaminated soils, air, and water, disrupting ecosystems and poisoning both wildlife and plant life, as well as microbiomes. Microplastics, particularly from food packaging, are found in soils and oceans, threatening food chains. Soil compaction due to intensive agriculture decreases its porosity and health, reducing its ability to support microbial and plant life. Deforestation and deep plowing for the expansion of crops and livestock destroy natural habitats, while the extermination of animal species deemed harmful has led to further ecological imbalance. Approximately one million species are currently threatened with extinction at an unprecedented rate not seen in millions of years, resulting in a major and irreversible crisis of global biodiversity.

No water, no life, no food

There is only 3% fresh water (H₂O) on the ‘blue planet,’ and only about 1% of this is easily accessible for human use. Of this accessible freshwater, almost 60% is artificialised, mainly through reservoirs and canals, and around 70% is used for agricultural production. Climate change, pollution, and overexploitation are threatening freshwater resources and seriously affecting the ‘ecosystem services’ they provide, such as water purification, climate regulation, flood control, and the maintenance of aquatic habitats and their biodiversity. Conflicts over access to and control of freshwater have existed since time immemorial. Their frequency and intensity have increased with population growth and environmental pressures, exacerbating geopolitical tensions and threatening global security, while at the same time giving rise to major migratory flows. Nine out of 195 countries account for 60% of all river water.

The impact of climate change on agricultural production

Extreme weather events (droughts, hurricanes, hail, floods, etc.) can devastate crops, leading to significant economic losses and food shortages. Rising temperatures affect agricultural yields by reducing photosynthesis. It also facilitates the arrival of new pests and fungi that threaten crops on a large scale. Rising sea levels will degrade coastal agricultural land, reducing production capacity in certain vulnerable regions. Rising CO₂ levels in the atmosphere may initially stimulate plant growth, but ultimately reduce their nutritional value and long-term yield. These phenomena, the occurrence and magnitude of which are unpredictable and uncontrollable, threaten global food security and the sustainability of agricultural systems. Without a paradigm shift, the current production system will continue to create the conditions for its own decline.

Sharing land and oceans between conservation and exploitation

The global food system is facing the colossal challenge of feeding a population estimated at potentially ten billion people by 2050. If we are to feed 25% more people than we do today in a sustainable way climate and environmental scientists have established the absolute necessity of keeping at least 50% of land and ocean surfaces free from exploitation. This is inconceivable without a change in the governance of issues relating to the food system at all levels, local, national, and international, so that production is directed primarily towards satisfying the objectively identified needs of the whole of humanity, and not just the geographically or economically most advantaged populations. Enlightened governance at all levels should promote a balanced diet that respects the planet’s capacity to support human life and biological diversity.

Towards a more sustainable food system? Who must choose? Who must take responsibility?

The global food system is a complex network comprising a wide variety of actors, each of which plays a decisive role in its functioning and evolution. It provides employment for over a billion people. Depending on the context, farmers, farm owners, and other food producers and processors more or less freely determine the cultivation and production methods that directly impact ecosystems and human health. Distributors and retailers shape supply chains and access to food products. Industrial producers and professional cooks choose ingredients and processes that are either favourable or detrimental to the environment and health. Together, they determine the ‘offer.’ Governments and international organisations are responsible for drawing up laws and regulations that govern working conditions in various sectors, as well as agricultural and commercial practices and the quality control of foodstuffs placed on the market. They also issue nutrition recommendations. Scientists and NGOs raise awareness and innovate to find solutions that protect health and the environment. Through their purchasing behaviour, consumers create ‘demand.’ They directly influence the evolution of the food system towards more or less sustainable practices. Each individual has a more or less free and informed choice of the food he or she wants to eat. Each family can define what it wants to provide for its members, without necessarily having the means to do so.