A 25,000-year tropical climate history from Bolivian ice cores

Ice cores that were recovered from the summit of Sajama mountain in Bolivia provide carbon-14-dated tropical records and extend to the Late Glacial St age (LGS). Oxygen isotopic ratios of the ice decreased 5.4 per mil between the early Holocene and the Last Glacial Maximum, which is consistent with v alues from other ice cores, The abrupt onset and termination of a Younger D ryas-type event suggest atmospheric processes as the probable drivers. Regi onal accumulation increased during the LGS, during deglaciation, and over t he past 3000 years, which is concurrent with higher water levels in regiona l paleolakes. Unlike polar cores, Sajama glacial ice contains eight times L ess dust than the Holocene ice, which reflects wetter conditions and extens ive snow cover.