The typical rainfall anomaly associated with ENSO is a dipole rainfall pattern: Eastern Africa is in phase with warm ENSO episodes, whereas southern Africa is negatively correlated with these events (Nicholson and Kim, 1997).Humans have adapted to patterns of climate variability through land-use systems that minimize risk, with agricultural calendars that are closely tuned to typical conditions and choices of crops and animal husbandry that best reflect prevailing conditions. Rapid changes in this variability may severely disrupt production systems and livelihoods, leaving little room for adaptation. Interannual variability of the African climate is determined by several factors.
The El Niño-Southern Oscillation (ENSO) is the most dominant perturbation responsible for interannual climate variability over eastern and southern Africa (Nicholson and Entekhapi, 1986). The 1997-1998 ENSO event resulted in extreme wet conditions over eastern Africa (while the 1999-2000 La Niña may have caused devastating floods in Mozambique).
Although predictions of ENSO have improved over the years, a lot remains to be done before scientists are able to predict spatial patterns of impacts with certainty to allow adaptive responses to be developed. The oceans seem to play an important role in affecting rainfall particularly for East Africa in the case of the Indian Ocean. Sea-surface temperatures are thus an important indicator for monitoring drought and heavy rain conditions over Africa.