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| Rapid changes in the mechanism of ocean convection during the last glacial period |
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| Author(s): Dokken TM, Jansen E |
| Source: NATURE Volume: 401 Issue: 6752 Pages: 458-461 Published: SEP 30 1999 |
| Times Cited: 120 References: 30 |
| Abstract: High-amplitude, rapid climate fluctuations are common features of glacial times. The prominent changes in air temperature recorded in the Greenland ice cores(1,2) are coherent with shifts in the magnitude of the northward heat flux carried by the North Atlantic surface ocean(3,4); changes in the ocean's thermohaline circulation are a key component in many explanations of this climate flickering(5). Here we use stable-isotope and other sedimentological data to reveal specific oceanic reorganizations during these rapid climate-change events. Deep water was generated more or less continuously in the Nordic Seas during the latter part of the last glacial period (60 to 10 thousand years ago), but by two different mechanisms, The deep-water formation occurred by convection in the open ocean during warmer periods (interstadials), But during colder phases (stadials), a freshening of the surface ocean reduced or stopped open-ocean convection, and deep-water formation was instead driven by brine-release during sea-ice freezing. These shifting magnitudes and modes nested within the overall continuity of deep-water formation were probably important for the structuring and rapidity of the prevailing climate changes. |
| Document Type: Article |
| Language: English |
| Reprint Address: Dokken, TM (reprint author), Univ Bergen, Dept Geol, Allegt 41, N-5007 Bergen, Norway |
Addresses:
1. Univ Bergen, Dept Geol, N-5007 Bergen, Norway
2. Nansen Environm & Remote Sensing Ctr, Bergen, Norway
3. Univ Courses Svalbard UNIS, N-9170 Longyearbyen, Norway |
| Publisher: MACMILLAN MAGAZINES LTD, PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND |
| Subject Category: Multidisciplinary Sciences |
| IDS Number: 243DF |
| ISSN: 0028-0836 |
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