Unstable Climate Conditions

Science  12 Feb 1999:
Vol. 283, Issue 5404, pp. 901d
DOI: 10.1126/science.283.5404.901d

It has been shown that the last glacial period (approximately 100,000 to 20,000 years ago) was characterized by millennial-scale temperature variability as well as major iceberg discharges and faunal shifts. The amplitude of this variability was larger during the last glacial period than during the present interglacial. McManus et al. (p. 971) have analyzed marine sediments from the North Atlantic and show that similar variability occurred in the previous glacial and interglacial periods of the last 500,000 years, and that the variability tends to be greater in glacial than in interglacial periods. They propose a model in which threshold ice volume and sea-level conditions exist for high-amplitude climate variability. These conditions represent a relatively small departure from our present ice-sheet and sea-level conditions.

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