High resolution tropical climate record for the last 6,000 years

Planktonic foraminiferal oxygen isotope records from the Cariaco Basin, offshore Venezuela were used to construct high-resolution tropical Atlantic climate records for the mid to late Holocene. Our results indicate that major increases in δ¹⁸O due both to increases in salinity and decreases in sea surface temperature occurred at least six times over the last 6,000 years (∼6,000-5,000, 4,500-4,200, 3,800-3,200, 3,000-2,800, 2,200-2,000, and 1200-800 cal yrs. B.P.). The initial δ¹⁸O increase centered at 5,500 years ago is coincident with the development of arid conditions in the Caribbean region and the end of the "African humid period" indicating a global drying of the northern tropics at this time. Synchronous with the aridification of the Caribbean region are the onset of wetter conditions in the South American Altiplano and the reoccupation of this region by humans. This combination of contrasting climate conditions is attributed to a southward displacement of the Inter-Tropical Convergence Zone (ITCZ) that would have resulted in decreased precipitation and increased trade wind intensity in the Caribbean region and increased rainfall over the Altiplano.