Climate and hydrological changes in tropical Africa during the past million years

Tropical African climate has oscillated between markedly wetter and drier conditions on all timescales in response to global climate disturbances. A step-like increase in aridity over the past 3 Ma has been primarily paced by orbital cycles coupled with the onset and amplification of high-latitude glacial cycles. On the 10⁴ –10³ -ka timescales, observed changes imply interactions between insolation, sea-surface conditions and vegetation. High-frequency variations could be linked to oscillations in major atmospheric circulation modes, in solar output, or to major volcanic events.