North Atlantic Intermediate Water Variability Over The Past 20,000 Years

North Atlantic intermediate-water temperature variations based on ostracod Mg/Ca ratios from Ocean Drilling Program (ODP) Hole 1055B document a series of multi-centennial-scale abrupt warming events throughout the last deglaciation and Holocene (up to similar to 3 degrees C). These events are coherent with abrupt climate reversals including Heinrich event 1, the Younger Dryas-Intra-Allerod cold period, and Holocene North Atlantic Deep Water (NADW) reduction periods. Deglacial-Holocene warm events were likely related to reduction in the strength of the upper NADW (Labrador Sea Water). We also found a long-term cooling trend in the ODP 1055 Mg/Ca record indicating continuous Labrador Sea Water strengthening throughout the Holocene. Our results help to better understand deglacial-Holocene upper NADW dynamics that remain poorly understood but can be important for regional and global climates.