Roche D, Paillard D, Cortijo E
IPSL/Laboratoire des Sciences du Climat et de l'Environnement, CEA-CNRS, 91191 Gif sur Yvette, France.
Nature. 2004 Nov 18;432(7015):379-82. doi: 10.1038/nature03059.
Heinrich events--abrupt climate cooling events due to ice-sheet instability that occurred during the last glacial period--are recorded in sediment cores throughout the North Atlantic Ocean. Modelling studies have described likely physical mechanisms for these events, but the quantitative characteristics of Heinrich events are less well known. Here we use a climate model of intermediate complexity that explicitly calculates the distribution of oxygen isotopes in the oceans to simulate Heinrich event 4 at about 40,000 yr ago. We compare an ensemble of scenarios for this Heinrich event with oxygen isotope data measured in foraminiferal calcite of a comprehensive set of sediment cores. From this comparison, we obtain a duration of 250 +/- 150 yr and an ice release of 2 +/- 1 m sea-level equivalent for Heinrich event 4, significantly reducing the uncertainties in both values compared to earlier estimates of up to 2,000 yr and 15 m of sea-level equivalent ice release, respectively. Our results indicate that the consequences of Heinrich events may have been less severe than previously assumed, at least with respect to Greenland climate and sea level.
海因里希事件——末次冰期期间因冰盖不稳定而发生的气候突然变冷事件——记录在北大西洋各地的沉积物岩芯中。模型研究已经描述了这些事件可能的物理机制，但海因里希事件的定量特征却鲜为人知。在此，我们使用一个中等复杂度的气候模型，该模型明确计算海洋中氧同位素的分布，以模拟约4万年前的海因里希事件4。我们将该海因里希事件的一组情景与在一套全面的沉积物岩芯的有孔虫方解石中测量的氧同位素数据进行比较。通过这种比较，我们得出海因里希事件4的持续时间为250±150年，海平面当量的冰释放量为2±1米，与之前分别高达2000年和15米海平面当量冰释放量的估计相比，显著降低了这两个数值的不确定性。我们的结果表明，至少就格陵兰岛气候和海平面而言，海因里希事件的后果可能没有之前假设的那么严重。
