Glossary: R

Here you will find definitions of terms used in resources on the Foodsource website. You will also find these definitions on the right-hand side within chapters. If you have any suggestions for new glossary items, let us know here.

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Radiative efficiency

A measure of ‘greenhouse strength’ for different greenhouse gases, defined as the change in radiative forcing per change in atmospheric concentration of a gas (in Watts per metre square per part per billion; W m-2 ppb-1).

Radiative forcing

The measure of how different factors (including greenhouse gases) change the balance between incoming and outgoing energy in the atmosphere. Expressed as the change in energy balance per unit area (in Watts per metre square; W m-2) over a given timeframe – typically contemporary compared to preindustrial conditions.

Reduction fishery

A fishery that catches wild fish to be converted into fishmeal and fish oil (often to supply the aquaculture sector), rather than catching fish for direct human consumption.


In the context of food system sustainability, the concept of resilience refers to the ability of the food system to cope with and recover from socio-economic or environmental shocks and pressures. A resilient system has a certain degree of toughness and is able to bounce back against or adapt to disturbances. A resilient food system, for example, is able to keep providing food or other outputs such as livelihoods for farmers, drinking water, and biodiversity conservation under conditions of drought, a drop in food prices, war, climate change, the spread of virus in plants or animals, and so on. Resilience can be thought of at different scale levels. For example, what may be considered as resilient on a national level may not be understood to be resilient at a farm level. While some see resilience as synchronous with sustainability, others point out that a resilient system may also be one that resists needed transformation; an unsustainable status quo may in fact be resilient to change.


is a mammal with a four-compartmented stomach which enables it to acquire nutrients from plant-based food such as grasses, husks and stalks. Examples of ruminants include cattle, sheep, goats, deer, giraffes and camels. After swallowing, microbes in the ruminant’s rumen (its first stomach compartment) begin fermenting the food. This process generates fatty acids (nutrients which the ruminant absorbs through its rumen walls) and methane, which the ruminant eructs or burps. Through this process, ruminants are able to digest coarse cellulosic material which monogastrics and people cannot. Methane emissions from ruminants are a significant source of greenhouse gasses from ruminant-based livestock systems.


Ruminant animals are distinguished by their specialised digestive system and include species such as cattle, sheep, goats, deer, and camels. In particular, their large rumen stomach allows plant matter to be regurgitated, chewed again, and for microbes to ferment it. This breaks down plant matter into digestible molecules that can be absorbed by the animal and allows ruminants to be fed on coarse plant matter such as grass, whereas other species such as pigs and chickens cannot.