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The Rains of Change
Approximately 500 to 400 thousand years ago, a fundamental change in the nature of glacial cycles occurred, including a shift to larger amplitude variations in atmospheric carbon dioxide concentrations and global temperatures. Meckler et al. (p. 1301, published online 3 May; see the Perspective by Kurita) present a stalagmite record from Borneo which provides a record of precipitation from 550,000 to 200,000 years ago. The amount of regional precipitation was similar during all four of the interglacials during that interval, and drying events during glacial terminations corresponded with cooling events in high northern latitudes.
Abstract
Records of atmospheric carbon dioxide concentration (Pco2) and Antarctic temperature have revealed an intriguing change in the magnitude of interglacial warmth and Pco2 at around 430,000 years ago (430 ka), but the global climate repercussions of this change remain elusive. Here, we present a stalagmite-based reconstruction of tropical West Pacific hydroclimate from 570 to 210 ka. The results suggest similar regional precipitation amounts across the four interglacials contained in the record, implying that tropical hydroclimate was insensitive to interglacial differences in Pco2 and high-latitude temperature. In contrast, during glacial terminations, drying in the tropical West Pacific accompanied cooling events in northern high latitudes. Therefore, the tropical convective heat engine can either stabilize or amplify global climate change, depending on the nature of the climate forcing.
