5.08 - Analysis of Paleoclimate Records for Understanding the Tropical Hydrologic Cycle in Abrupt Climate Change

Abstract

Climate data over the past two decades show that abrupt millennial-scale climate changes brought dramatic changes in temperature and greenhouse gases during the last glacial–interglacial cycle. However, the millennial-scale changes in the tropics were associated with both dramatic weakening and strengthening of the hydrological cycle. The early Holocene was warmer and wetter than the present climate, resulting in over-spilling of North African lakes and overflow of rivers on the Indian subcontinent. In contrast, the late Holocene, accompanied by a dry and windy climate, is thought to be responsible for desertification of North Africa and reduced outflow of Indian subcontinent rivers. The prevalence of this dry climate during the late Holocene is inferred to have led to the decline or demise of many ancient civilizations.