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Heinrich event


In Heinrich events during the last glacial period?, ice shelves in the northern hemisphere rapidly melted, and many icebergs broke off from glaciers and floated across the North Atlantic. The icebergs contained rocks eroded by the glaciers, and as they melted these rocks fell to the sea floor. The resulting ice rafted debris is a major piece of evidence for these Heinrich events. Scientists drilling through marine sediments can see six Heinrich events in cores of mud retrieved from the sea floor, which are called H0-H6 going back in time.

Heinrich events are interesting because they may be evidence of abrupt climate change during the last glacial period. The events are rapid: they last around 750 years, and their onset may occur in just a few years:

During Heinrich events, huge amounts fresh water flow into the ocean. For Heinrich event 4, the fresh water flux has been estimated to approximately 310 53 \cdot 10^5 m3/s with a duration of 250±150 years, equivalent to a fresh water volume of about 2.3 million km3:

  • D. Roche, D. Paillard and E. Cortijo, Duration and iceberg volume of Heinrich event 4 from isotope modelling study, Nature 432 (2004), 379–382.

Here are rough dates for the Heinrich events, averaging data from various different sources listed in the Wikipedia article:

H010,000 BC
H115,000 BC
H222,000 BC
H330,000 BC
H437,000 BC
H540,000 BC
H6~60,000 BC

There appears to be a relation between Heinrich events and Dansgaard-Oeschger events, but there are more of the latter.



The graph at the top of this page, and the dates of Heinrich events, are taken from this references.

category: climate