### Agricultural trade

#### Indicators:

- Net Export and import of food crops / animal products
- Desired self sufficiency ratios of food crops / animal products

| #### Net export and import of food crops / animal products
| unit:1000 Gg/yr (teragram fresh weight per year) Dimension: region, crop product / animal product

Trade data for agricultural commodities for the 1970-1995 period are taken from the Food and Agriculture Organization of the United Nations (FAO). Trade flows are expressed for each region as export minus import. Positive values indicate net export of the product considered. Negative values indicate net import.

Net export or import is added to the consumption of food crops or the consumption of animal products to obtain the required production of crops and animal products in each region, which will subsequently form the input for the land-cover model (LCM). Trade in biofuels (i.e., processed biofuel crops) is simulated by the energy model TIMER.

Imports allow the demand for a specific crop or animal product to be statisfied in regions where the production capacity is limited. Exports lead to an additional demand for agricultural production and land in the exporting region.

| #### Desired self sufficiency ratios of food crops / animal products
| unit:prod./cons.(production cosumption ratio) Dimension: region, crop product / animal product

Food trade is determined by exogenous Desired Self-Sufficiency-Ratios (DSSRs). DSSRs are defined for each region and each food product as the ratio between production and consumption. Thus, exporting regions have DSSR values exceeding 1.0.

The exporting regions drive world trade, which means that the total amount of exported food is computed from the DSSR values of exporting regions. Total exports are added to a 'global basket', which is available to the importing regions. The DSSR values of importing regions (DSSR < 1.0) are used as scaling factors to allocate food from this global basket, so that global exports equal global imports.

The actual self-sufficiency ratios may deviate from the desired ones when the amount demanded by importing regions is not met by the exporting regions. In such cases the production of the importing region has to be increased to meet the domestic demand. When regions are not able to produce the demanded amount of food products, the demand (and human diet) will be modified, usually by a shift from luxury products to basic products.

The rules for determining the DSSRs are scenario dependent.