A 0.5-Million-Year Record of Millennial-Scale Climate Variability in the North Atlantic
Long, continuous, marine sediment records from the subpolar North Atlantic document the glacial modulation of regional climate instability throughout the past 0.5 million years. Whenever ice sheet size surpasses a critical threshold indicated by the benthic oxygen isotope (δ 18 O) value of 3.5 per m...
| Published in: | Science |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
American Association for the Advancement of Science (AAAS)
1999
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1126/science.283.5404.971 https://www.science.org/doi/pdf/10.1126/science.283.5404.971 |
| Summary: | Long, continuous, marine sediment records from the subpolar North Atlantic document the glacial modulation of regional climate instability throughout the past 0.5 million years. Whenever ice sheet size surpasses a critical threshold indicated by the benthic oxygen isotope (δ 18 O) value of 3.5 per mil during each of the past five glaciation cycles, indicators of iceberg discharge and sea-surface temperature display dramatically larger amplitudes of millennial-scale variability than when ice sheets are small. Sea-surface temperature oscillations of 1° to 2°C increase in size to approximately 4° to 6°C, and catastrophic iceberg discharges begin alternating repeatedly with brief quiescent intervals. The glacial growth associated with this amplification threshold represents a relatively small departure from the modern ice sheet configuration and sea level. Instability characterizes nearly all observed climate states, with the exception of a limited range of baseline conditions that includes the current Holocene interglacial. |
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