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Global climate changes (CC) evidently have an impact on the weather patterns caused by a marked increase in atmospheric temperatures. Subsequently, erratic weather patterns making weather prediction a problem. This in turn has impacted negatively on rain fed agriculture. Of all the climatic factors, the daily and inter-annual variation in precipitation is most crucial for rain fed agriculture and the runoff for irrigated production. The day-to-day variability of rainfall associated with weather is the major risk factor for most forms of agriculture. Soil moisture deficits, crop damage and crop diseases are all driven by rainfall and associated humidity. Variability in rainfall intensity and duration makes the performance of agricultural systems in relation to long-term climate trends very difficult to anticipate.
These changes will have serious impacts on the dimensions of food security in terms of availability, accessibility, quality, utilization and system stability. Changes in precipitation and evaporation will result to shifts in the existing patterns of soil moisture deficits, ground water recharge and runoff. Therefore, rain fed agriculture will exhibit more volatility as a result of moisture stress in regions with declining rainfall. Areas with increased rainfall and temperature will exhibit increased crop damage, deaths of livestock, increase in crop and livestock diseases and soil erosion. Large areas of irrigated land associated with river basin deltas will be affected by a combination of reduced inflows, salinity, annual flood cycles and sea level rise. The flood water may subsequently introduce pollutants from urban areas to the farmed lands posing health related hazards like biomagnification of heavy metals in crops and fish. These stresses on some of the prime productive land will continue to reduce agricultural output, biodiversity and natural ability to recover.
The key implications from studies from runoff modeling indicate a shift in potential for cereal production to developed countries. Hydrological regimes and after resources will also be affected. Changes in rainfall patterns (intensity-duration-frequency) will determine crop growth, crop damage and status of aquatic environments. Hydrological process will exhibit more variability. Subsequently increased water loss from evaporation from natural water bodies and reservoirs caused by increased temperatures poses a problem on irrigation depended agriculture, fisheries and aquaculture. Prolonged drought may cause hamper livestock production practiced by pastoralists due to lack of pasture and water. The changes will also affect secondary agricultural production mainly food processing, cold storage, transport and intensive production. This will lead to higher market values for land and water. Later food products will become expensive and unavailable especially for the poor.
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