Early warning is the provision of early and relevant information on potential or actual disasters and their impacts. While the aspects relating to establishing early warning systems were presented in the phase 2 booklet on preparedness, this booklet focuses specifically on the provision of early warning information through FAO's Global Information and Early Warning System (GIEWS).
GIEWS continuously monitors the food supply and demand situation around the world, and reports to the international community through its system of regular and ad hoc reports. GIEWS and similar early warning work carried out by regional, national and sub-national early warning and food information systems which FAO supports, play a crucial role in ensuring that timely and appropriate action can be taken when an emergency arises.
FAO also monitors, provides early warning on, and acts to control outbreaks of transboundary diseases and migratory pests through its EMPRES programme (Emergency Prevention System for Transboundary Animal and Plant Pests and Diseases). Reference is made to the respective Section on EMPRES in the phase 1 booklet on prevention.
Global Early Warning: What FAO does FAO's Global Information and Early Warning System (GIEWS) monitors all aspects of food supply and demand and food security at global, regional/sub-regional, national and sub-national levels. It provides the international community with the most accurate, current independent information through a system of regular and periodic reports. Its main objective is to provide early warning of imminent food crises to ensure timely interventions in countries or regions affected by natural or man-made disasters. Inputs into GIEWS include information provided by regional and national early warning systems. FAO monitors the plant and animal health situation around the world, providing early warning for outbreaks of transboundary animal and plant pests. |
GIEWS is based at FAO Headquarters in Rome and managed by the Global Information and Early Warning Service (ESCG). Now a world-wide network, GIEWS includes 116 governments, three regional organizations, and 61 NGOs as well as trade, research and media organizations. The system monitors food supply and demand in all countries - FAO Members and non-members alike - on a continuous basis. Particular emphasis is placed on countries and regions where food emergencies are most likely to occur, and in particular the low-income food-deficit countries (LIFDCs) which are most vulnerable to crop failure or high world cereal prices.
At the national level, GIEWS estimates are made for all LIFDCs at the beginning of each marketing year. These estimates include the quantities of imports and the level of food assistance required to maintain consumption at normal levels. Commercial imports and food aid deliveries are monitored year round to reveal periods of shortage and donors are advised of opportunities for food purchases locally or in neighbouring countries.
The main focus of the analysis is on cereals. Up-to-date information on other food types is often weak. GIEWS is, however, improving its coverage of non-cereal food staples in countries where such foods form a large part of the national diet. Coverage may also be broadened to include nutritional indicators through the global nutrition monitoring system being developed by FAO's Food and Nutrition Division (ESN). The division will use data collected at the national level on the nature, extent, magnitude and severity of different types of nutritional problems and their evolution.
National level data is aggregated at a global level and combined with information on global market export prices and traded volumes on major grain exchanges. This provides an independent source of information on world market conditions and prospects for food commodities, including warnings of any risk of major rises in food prices. Aggregation is also carried out at regional and sub-regional levels.
Monitoring food security at the sub-national level, especially that of food- insecure groups of the population, is an expanding area of GIEWS's work. Information is collected on indicators of food crises. Data regarding local market conditions and `coping' behaviour such as unusual asset sales, labour migration, consumption of wild foods or reduced food intake is collected. Data on indicators of malnutrition, food-related morbidity and mortality are also monitored when they are available. This work has been boosted by the RiskMap project. It will be further strengthened by the FAO-co-ordinated Food Insecurity and Vulnerability Information and Mapping System (FIVIMS) initiative which emerged from the World Food Summit in 1996 (see Phase Two - Preparedness).
Main information sources for GIEWS monitoring are:
GIEWS officers are able to draw on around 20 years of time-series statistics together with background information. This data on food production, trade, food aid, stocks, consumption and sub-national food security is continuously updated and is constantly analysed. Carried out by the FAO-supported regional and national food security information systems, this analysis relies on a range of techniques and tools which were developed with FAO involvement. Some of the more important ones are briefly described in the following sections.
GIEWS makes use of two indices derived from remote sensing data in its regular monitoring: Cold Cloud Duration Index (CCD) and Normalized Difference Vegetation Index (NDVI).
CCD is derived from data for infra-red reflectivity, and is an index of the duration of cloud coverage over a ten-day period. Such cloud extends to a high altitude and is likely to be rain-bearing. ARTEMIS, managed by FAO's Environment and Natural Resources Service (SDRN), receives the data directly from Eumetsat's high-altitude geostationary METEOSAT satellite. This satellite covers the African continent and processes the information to provide CCD data sets and images for regions of Africa on a ten-day basis. ARTEMIS also provides CCD images for Southeast Asia based on data obtained from the Japanese GMS satellite.
As an indicator of the likelihood of rainfall, the CCD index provides useful corroborating evidence when used in conjunction with meteorological data, though it is not a substitute for the latter. Research is in progress within and outside FAO to establish the strength and nature of the relationship between the CCD index and actual precipitation for different locations and times of the year.
NDVI provides an indication of the amount and state of vegetative ground cover, and thus the effect of weather conditions on plant growth. The index is derived from advanced very high resolution radiometry (AVHRR) data acquired by the United States National Oceanographic and Atmospheric Administration (NOAA) network of low-altitude polar-orbiting satellites, and processed into NDVI data and images over 10-day periods for all major regions of the globe by the NASA Goddard Space Flight Centre.
It is not possible in NDVI images to distinguish between crops and other vegetation in areas of small scale agriculture. However, if planting and harvesting times of dominant cultivars are known for a given location, the progression of NDVI over the season compared with previous years can signal whether or not crops are likely to be subject to severe moisture stress at particular times. Inferences can also be made as to the state of pastures compared with previous seasons.
In tropical rainfed agricultural systems, where rainfall and potential evapo-transpiration are likely to be key determinants of crop yield, agrometeorological crop estimation can be carried out using water balance models. FAO has developed a Crop Specific Soil Water Balance model, which generates the Crop Water Satisfaction Index (CWSI). This represents the cumulative percentage of crop water requirements which have been met at any point in the growing season for a given crop variety. The information derived from these models, as well as the current season's agrometeorological trends are provided to GIEWS for use in crop and food supply assessments.
The data required for establishing the model for a particular crop variety and location include crop water requirements throughout the growing cycle, crop maturation time, latitude, longitude, normal potential evapotranspiration, and soil water retention characteristics. Current season data requirements are crop variety, time of planting, rainfall and (preferably) potential evapotranspiration over ten days.
Estimates of actual crop yield using this method can be produced only on the basis of regression analysis to estimate the historic relationship between CWSI and yield within specific farming systems. This enables additional information to be taken into account, for example fertiliser application rates, weeding and other aspects of husbandry, which tend to remain constant from year to year. Even so, the predictive power of the index is subject to year-to-year variability in these factors and to unpredictable yield influencing events such as pest and disease attacks or extreme weather.
Several techniques of weather monitoring are in use, for instance the comparison of actual rainfall with the normal value. Recently, the SADC Regional Early Warning System has started using El Nino Southern Oscillation (ENSO) index (ISO) values to predict the likely outcome of the ongoing rainy season. The behaviour of ENSO-ISO during wetter years has been observed to differ consistently from that in drier years. By comparing the behaviour of ISO during the current year against that in typical wet and dry years, it is possible to evaluate whether the current season is closer to the "dry" or to the "wet" pattern.
A range of computer-based software tools have been developed by FAO for early warning purposes. These fall into five main groups:
Baseline' or `reference' data is essential for the effective interpretation of monitoring data on food security indicators. In addition to the profiles developed through RiskMap and the large amount of CCBS data assembled by GIEWS, FAO has assembled a number of databases covering remote sensing, climatology and farming practices in countries where it has supported food security information systems. The most important are:
GIEWS monitoring information is disseminated globally to donors, international organizations, governments, NGOs, research organizations and other interested parties by means of a range of regular and ad hoc media:
GIEWS uses many different channels to disseminate its reports. In addition to printed copies distributed by mail, reports are dispatched by fax and E-mail to interested organizations. GIEWS also has a World Wide Web site (<http://www.fao.org> under "Global Watch" or "Economics") which provides Internet access to all outputs in English, French and sometimes Spanish. It also contributes to ReliefWeb (see Phase Two - Preparedness).
FAO's work in monitoring is an important aspect of early warning with obvious links to food supply monitoring. (See Phase One - Prevention). Outputs are fed directly into GIEWS as noted above.
FAO Guidelines and Reference Manuals
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