Coast and highland paleoclimate of the north-central Peruvian Andes and its influence on coastal water availability and cultural development, 6000 to 2000 cal BP

Abstract

Paleoclimate records from highland and coastal contexts are synthesized for Peru's north-central coast with a focus on the period from 6000 to 2000 cal yr BP. Around 6000 cal yr BP, both the highlands and coast experienced considerable climatic change. Increased precipitation in the southern tropical Andes ended a long period of aridity, resulting in higher lake levels and renewed glacial activity. Meanwhile, the north and central coasts experienced a major shift in the El Niño-Southern Oscillation that may have accompanied a change in background sea surface temperatures. Between 4000 and 3500 cal yr BP, glaciers began to retreat even as the South American Summer Monsoon strengthened, signaling a shift to warmer temperatures and continued increases in highland precipitation. Around 3000 cal yr BP, El Niño abruptly increased in frequency to near-modern intervals, with more frequent rain events on the coast and greater climate variability in the highlands, including notable periods of drought. This synthesis highlights areas in which more work is needed to improve understanding of paleoclimate change and its effects on water availability, including disentangling the effects of precipitation and temperature on water balance, reconstructing changes in coastal humidity, and investigating the relative influence of coastal and highland climate regimes over the middle elevations of the western Andean slope.