HOLOCENE CLIMATE CHANGE IN THE TROPICS: EVIDENCE OF ABRUPT CLIMATE CHANGE PAST AND PRESENT

Abrupt climate change now underway in the Peruvian Andes is placed within a longer time perspective using additional tropical ice core records augmented by a 5200-year old plant exposed in 2002 by the retreating ice. The well-preserved plant provides evidence that: (1) the Quelccaya ice cap is older than the originally determined age of 1.5 ka; (2) temperatures in the high Peruvian Andes were warmer before 5.2 ka than after; and (3) climate conditions abruptly reversed about 5.2 ka following a cold, humid event that buried the plant growing at 5200 m asl. An abrupt mid-Holocene cold event marked the transition from an early Holocene "Hypsithermal" to a cool, late Holocene "Neoglacial" and was widespread and coincident with structural changes within several civilizations. Abrupt climate change has also been documented around 4 ka in the tropical ice cores, coincident with the "First Dark Age," the period of the greatest historically recorded drought in tropical Africa, which apparently extended to the Middle East, western Asia and into tropical South America.