Using Akwa Ibom State as an example, this paper justifies the need for a GIS based land use/land cover change early warning system. The components and capabilities of the system are examined. A digital database for the early warning system is created. As part of the database, land use/land cover maps of the area for the period 1984 to 2003 were produced using standardized methodologies such as the FAO Land cover classification system. The Land use/Land cover maps were produced from Landsat TM satellite data using supervised classification. For change detection, the classified images were compared at pixel level. Using this approach, the location, nature and direction of land use/land cover changes were modelled. Urban growth and development in the area was also modelled. Furthermore, water samples were taken from rivers for analysis to determine the water quality. Personal interviews of community leaders were carried out at different randomly chosen locations to determine past and present status of biodiversity in the area. The implications of observed changes in landuse/land cover on water quality, climate, biodiversity, and food security in the area were examined using a GIS based approach. The Early Warning System based analysis reveals that some urban centres have expanded into farmlands/fallow lands and surrounding secondary forest, quite a number of plant and animal species have been lost. As a result, food supplies [especially vegetables and staple foods] to a number of urban centres have been reduced. This has also affected the means of livelihood of many farmers, especially those involved in market gardening in the area. Also the quality of some of the surface water within and around urban, rural, industrial and agricultural areas has been degraded by excessive amounts of sediments, heavy metals, phosphorus, nitrogen and sodium. Many urban centres are now experiencing higher temperatures and rainfall than before resulting in occasional flooding, landslides, water pollution and soil erosion. In summary, as a result of changes in land use/land cover, many areas are now vulnerable to gully erosion, landslide, flooding, air pollution, water pollution, land pollution and above all food insecurity. In conclusion, this study shows that with the land use/land cover change early warning system, it is possible to - among other things - monitor and manage human activities within and around urban centres to ensure a fairly stable favourable climate, water and food security in future.