A 22,000-Year Record of Monsoonal Precipitation from Northern Chile's Atacama Desert

Abstract

Fossil rodent middens and wetland deposits from the central Atacama Desert (22 degrees to 24 degrees S) indicate increasing summer precipitation, grass cover, and groundwater levels from 16.2 to 10.5 calendar kiloyears before present (ky B.P.). Higher elevation shrubs and summer-flowering grasses expanded downslope across what is now the edge of Absolute Desert, a broad expanse now largely devoid of rainfall and vegetation. Paradoxically, this pluvial period coincided with the summer insolation minimum and reduced adiabatic heating over the central Andes. Summer precipitation over the central Andes and central Atacama may depend on remote teleconnections between seasonal insolation forcing in both hemispheres, the Asian monsoon, and Pacific sea surface temperature gradients. A less pronounced episode of higher groundwater levels in the central Atacama from 8 to 3 ky B.P. conflicts with an extreme lowstand of Lake Titicaca, indicating either different climatic forcing or different response times and sensitivities to climatic change.

Banana Crop Expansion and Increased River-borne Sediment Exports to the Gulf of Urabá, Caribbean Coast of Colombia

“…As discussed, Haug et al (2001) results in marine sediment from the Cariaco basin of Venezuela align with reconstructed precipitation in the circum-Caribbean region. At the same time, these results show a reverse correlation with reconstructed precipitation on the eastern Pacific (Betancourt et al, 2000;Conroy et al, 2008). Consequently, our results reflect the proposal in which precipitation onto and runoff from northern South America into the Caribbean decreased during the late Holocene, owing to more southerly positions of the ITCZ and increased ENSO frequency (Haug et al, 2001;Peterson and Haug, 2006;Sachs et al, 2009).…”

Emergence of social complexity among coastal hunter-gatherers in the Atacama Desert of northern Chile

“…Whereas the main hyperarid "core" of the desert has remained thus for millions of years (but see ref. 17), the eastern and southern margins have fluctuated considerably during the Pleistocene and Holocene (18)(19)(20)(21). Although exact chronologies vary, most of these records agree on two pronounced wet phases at the end of the Pleistocene, documented by higher lake levels, plant invasions into what is today absolute desert, and elevated groundwater tables between 17.5-14.2 and 13.8-10 ka BP (17,22).…”

“…2). Rodent middens reveal the onset of extreme aridity in the central Atacama Desert between 4 and 5 ka BP (18,19). This coincided with the loss of complex funerary practices in the Chinchorro culture (Fig.…”

“…Intermittent periods of greater rainfall also occurred between 7.8 and 6.7 ka BP in the Andean highlands, as evidenced by the intermittent presence of perennial plants in areas of absolute desert during the Holocene (18,19,27). Increases in rainfall were coeval with increased aquifer discharge in the lowlands, causing the emergence of springs (aguadas) and watercourses along small creeks and ravines (28).…”

Holocene environmental changes in the highlands of the southern Peruvian Andes (14° S) and their impact on pre-Columbian cultures

“…Nonetheless, records of midHolocene climate conditions are not synchronous in the central Andes (Betancourt et al, 2000;Holmgren et al, 2001;Abbott et al, 2003;Latorre et al, 2003;Kuentz et al, 2011). Discrepancies in the exact timing of climatic changes and the interpretation of their causes are common as proxy records are obtained from different archives and geographically heterogeneous localities.…”