Define "sustainability." If your focus is only on the "environmental impact", the definition is far too narrow. Economics? Human health and satisfaction? All of these must be weighed in the equation. Local food systems can play a role, for sure. They offer a means to reducing food miles, but may not actually improve environmental outcomes. For example, want tomatoes in Norway? Well, that is likely going to involve energy intensive green house production systems. It would be local...but not necessarily less carbon footprint than Greek tomatoes shipped to Norway. Promoting or requiring local food production necessarily implies trade-offs. Less food choice. Higher food costs. Maybe trading one environmental "bad" for another... It certainly has a place...how big a place remains to be seen.

What could be the contribution of local food production to the sustainability of food system?

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In areas such as island nations the role of a local food system is particularly important. In Hawaii and Puerto Rico over 90% of the food is imported. This makes the food system vulnerable as the case of the Hurricane that recently devastated the island of Puerto Rico.

In our electrical system we understand that having a duplication for the generation system can give security not found in a centralized system where things cannot easily redistribute. There are problems in putting everything into one basket. Diversified local production gives ability to weather disaster local conditions and to recover from them which a centralized system does not.

Another point I would like to bring to the table and stress is that the value of the local food is superior . It is well investigated that consuming fresh and fresh vegetables and fruits are the cornerstone of healthy diet. Considering that 80% of all diseases have significant diet component the value of local food production cannot be overemphasized as medical costs are threatening to bankrupt the developed world. Obesity which represents a growing issue globally is related with over consumption of over processed over adulterated so called food which have little nutrition in them.

Besides the degraded nature of convenient so call food products many of negative inpacts on our food system are related to use of heavy fertilizer and pesticide inputs. When locally available materials are used as the basis of soil fertility the dependency on these dangerous inputs can be greatly reduced and eliminated. The dependency on pesticides and fertilizers are the root of many of critical environmental issues our society presently grapples with.

Thirdly I would like to the economic potential for the generation of local food production. When food is produced locally by local farms they can recirculate their incomes into the local economy producing a multiplier effect. When local production is available it can generate local value added opportunities. Finally the culture around food is something that can add to identity. Ultimately we will be impaired if we lose our pride in who we are and how we interact with where we live.

In our food system up to 25% of the carbon foot print is not related to production practice but rather is related to processing packaging and distribution. One of the inefficiency of our centralized systems of food production is the confined animal feeding operations. This abomination transfers the fertility of our global soils and redisdistributes them to areas which result in eutrophication of our global esturaies and damages our water system.

Distributed local production of animal and crops can repait the consequences of a centralized industrialized mind set that does not take into consideration the quality of the food, the well fare of our animals, nor the environmental, energetic or health consequences.

It would be easier to look at your question from the opposite side. What is the contribution of sustainable food systems to local food production? This is because, local food production is not local food production is not universally the same. So we may want to know to what extent sustainability of food systems will lead to local food production. From this approach then, for whatever food system we are referring to we start to ask ourselves to what extend are they sustainable, to what extent can the production be sustained, what is required for production to be sustainably intensified, etc. Just my thinking.

Thanks to all for your interesting answers.

@Darren, what I mean for sustainability? Well, not only "environmental impact". I think is too important to take in consideration many other aspects, for example: sustain local economy; social aspect; food quality; biodiversity; health and safety of consumers; ect. considering also the fact that we have to be careful to not compromise the future.

The neglect of the native food systems and blind adoption of Western Prescriptions has been the bane of Indian agriculture.

The sustainability of the food system must consider environmental, economic and social issues. A country or region within a country (especially if the country has a large area) that is not capable of producing a staple food for its population, will affect any of the issues related to the sustainability of the food system. I believe that the economic and social issues will be the most affected, especially in the minor economic income sectors of the population.

The local food production is strongly related to the history and food culture of its inhabitants. To promote the local food production based on tacit knowledge of farmers and the explicit knowledge, maintaining adequate standards of food quality, safe and healthy food and good agricultural practices, is a way to achieve the sustainability of the food system and this will contribute to the food security.

We have to consider the comparative and competitive advantages when we are producing crops in general, because food security doesn’t mean that I as a country have to produce all necessary food but I can produce the crops that I have comparative advantage in it, and produce it cheaper, and export the other crops which I haven't comparative advantage in producing it and it is can be produced with high cost.