Organized by man, the whole agricultural sector is a food chain depending on fossil fuels. On top of this chain, the livestock sector relies entirely on the plant sector, which depends in particular on fertilizers and pesticides derived from gas and oil. The main purpose of this plant sector is – through photosynthesis – to store the light energy emitted by the sun in the form of sugar. It is from carbohydrates that plants and animals are then able to synthesize the other lipids and proteins necessary for life and therefore for our diet. It is in this regards that the photosynthetic reaction specific to the plant kingdom is a necessary condition for the survival of the biosphere and so, of mankind.

Over the course of the articles released in my blog, a logical path led me to believe that in the long term, the production of plants is threatened by the climatic disturbance to which their aerial part is exposed. In this respect, the trees will probably be the first victims of the disruption and the current crop practices are certainly not sustainable.

I think green algae – those that are capable of photosynthesis – are a possible counter to the threat. Hosted in an aqueous medium which acts as a buffer thanks to its thermal inertia, they are relatively protected from sudden variations of weather conditions. In addition, algae have the advantage over most other plants, and in particular over the major crops that are the basis of our diet, of occupying space in three dimensions. Distributed vertically, they are able to maximize the amount of photosynthetic light intercepted per unit area, for a minimized footprint.

In the same way as the vast majority of plants, green algae nevertheless depend on the supply of nitrogen which is essential for the synthesis of proteins, starting with that of chlorophyll. Today, agriculture provides for the needs of cultivated species by providing nitrogen fertilizer made from fossil fuels. However, we know that the production of those fertilizers is not sustainable in the long term. This is the reason why humanity will be on notice to rehabilitate the natural method of obtaining fertilizers from which the privileged family of legumes to which alfalfa, peas or beans belong. The production by these species of assimilable « primary » nitrogen is based in this case on the ability of symbiotic bacteria in the roots (Rhizobium) to fix the gaseous nitrogen naturally available in the air we breathe. This original metabolic pathway being exclusive to legumes, it make sense that they held their place for millennia in the three-year rotation system that prevailed before the generalization of monoculture which is concomitant with the fertilizer industry. In the absence of fossil fuels, the reduction of atmospheric nitrogen by the nitrifying bacteria usually hosted by the root system of legumes is therefore a necessary condition for crop production.

In short, the whole agriculture is based on two key natural processes: photosynthesis and the reduction of nitrogen in the air. Assuming that the scenario of a submerged plant sector is true for the reasons explained above, it must incorporate organisms that are able to reduce the nitrogen in the air to fertilize the algae. If this kind of organism does not already exist naturally in aquatic environments – of which a large part remains to be explored – I guess that man will soon be able to design them by using biotechnology. This decisive step would pave the way for the genesis of submerged ecosystems where such “augmented” organisms endowed with the potential of rhizobium would be associated with green algae. The accessibility to the air being essential to the process, one can imagine that a mechanical mixing of the surface of the water by means of either wind or photovoltaic energy sources would be part of the production system. Furthermore, the incorporation of other species able of synthesizing proteins could complement this type of artificial ecosystem to aim for food self-sufficiency. In the form of “autarkic” reactors integrated into agri-food smartgrids comparable to those currently emerging in the field of energy, such decentralized production units would make it possible to manufacture all the food necessary for the mankind in a sustainable way from only water, air and light. Relatively simple from an ecosystem point of view, this type of reactor, characterized by an small footprint, would be managed by means of smart process control technology.

This model, seen as a substitute for conventional agriculture which depends on both soil and fossil fuels, is the only one that seems to me susceptible to solve the issues of their scarcity on short notice. In the field of agriculture, we are today at a crossroads with many initiatives that aim to free ourselves from the soil and the climate. So-called indoor agriculture – i.e. agriculture in a totally controlled environment – ​​will be a major trend on a global scale with, in some cases, the aim of producing soilless animal protein from insects, for example. As an alternative to the meat industry, which now questions humanity because of its grip on the ground and also animal suffering, this option is however obsolete because it requires the production of plant feed upstream. This is why the production of algae as describes above, appears to me to be the only viable way to meet the food needs of human beings in the long term.