Methodology
The AEZ methodology follows an environmental approach; it provides a standardized framework for the characterization of climate, soil and terrain conditions relevant to agricultural production. Crop modeling and environmental matching procedures are used to identify crop-specific limitations of prevailing climate, soil and terrain resources, under assumed levels of inputs and management conditions. This part of the AEZ methodology provides maximum potential and agronomically attainable crop and biomass yields at a global level at 5 minute resolution grid-cells.
GAEZ 2000 Website
GAEZ 2002 report + CD

GAEZ 2009
New AEZ computations were completed for a range of climatic conditions, including reference climate (average of period 1961-1990), individual historical years from 1961- 2002, and scenarios of future climate based on the published outputs of various global climate models (IIASA 2002). Hence, the AEZ results consistently quantify impacts on land productivity of historical climate variability as well as of potential future climate change.

The information contained in these data sets forms the basis for several further AEZ applications. Examples are: the quantification of land productivity, the estimation of extents of land with quantified rain-fed or irrigated cultivation potential for respectively food, feed, fiber and bio-energy production, the occurrences of environmental constraints to agricultural production, the identification of potential ‘hot spots’ of agricultural conversion, and the possible geographical shifts of agricultural land potentials as result of changing climate. Finally, the results of AEZ land productivity assessments provide a spatially explicit and agronomically sound basis for applications of multi-criteria optimization of land resources use and development.

Global assessments of agricultural crop production is the third major revision since 2001. The current revision provides results for an expanded number of crops and management techniques GAEZ 2009, aims to include practical applications such as a significantly updated version (in CD ROM and Web-format), including expanded crop coverage and dryland management techniques.
The tasks for the third revision included:

• Creation of an updated and expanded global database with a number of additional crops including cocoa, coffee, tea, tobacco, yam and selected vegetables.
• Creation of a specific grassland suitability classification and its application worldwide.
• Introduction of new input/management classifications reflecting dryland management for the main crops grown in these conditions.
• Creation of GIS layers that reflect actual land use/land cover and crop distribution and production levels for both rain-fed and irrigated conditions.
• Comparison of potentially attainable yields with actual yields and interpretation in terms of land balances and yield gaps.

The updated assessments are based on new soil information and an enhanced terrain inventory.

• Latest harmonized SOTER and WISE soil databases of FAO and ISRIC.
• Updated terrain slope data based on 90m resolution DEM. The elevation data from the Shuttle Radar Topography Mission (SRTM) were made available by U.S. Geological Survey (USGS).
• Time series data are used from the Climate Research Unit’s 0.5 x 0.5 degree latitude/ longitude gridded monthly climate data for the period 1901-2002 (CRU TS 2.1; Mitchell & Jones, 2005).
• Latest global irrigation area inventory produced of FAO and Frankfurt-University.
• Latest global inventory and distribution of livestock produced by FAO in cooperation with other international institutions.

Latest crop yield and area statistics of FAOSTAT and Agriculture 2015/30.

Responsible for this page: Elisabeth Kawczynski
Last updated: 16 Oct 2009