Two ice cores from the col of Huascaran in the northcentral Andes of Peru contain a paleoclimatic history extending well into the Wisconsinan Glacial Stage and include evidence of the Younger Dryas cool phase. Glacial stage conditions at high elevations in the tropics appear as much as 8-12 degrees cooler, the atmosphere was 200 times dustier, and the Amazon Basin forest cover may have been 40 to 50 percent less extensive.
Differences in both 18O (8 per mil) and deuterium excess (4.5 per mil) from the Late Glacial Stage (LGS) to the Holocene are comparable with polar ice core records. These data imply that the tropical Atlantic was possibly 5-6oC cooler during the LGS, that the climate was warmest from 8,400 to 5,200 yr BP, and that it cooled gradually culminating with the Little Ice Age (200-500 yr BP). A strong warming has dominated the last two centuries.
