Analysis of sea-surface temperature in the Indian Ocean shows that warming correlates with east African rainfall; the effect on atmospheric convection and precipitation over the Indian Ocean is greater than that associated with El NiƱo (ENSO).
Article from Water Supply Paper 2375 summarizing the correlation of precipitation, temperature, and atmospheric moisture with the frequency and intensity of a drought.
Article from American Scientist on study of the San Francisco Bay estuary as a component of the global climate system showing that natural fluctuations might be mistaken for anthropogenic trends affecting waterflow and salinity.