Heinrich event
A Heinrich event is one of the events which occurred during the coldest point of Bond Cycles in which many icebergs were discharged into the North Atlantic and melted.
Evidence for this can be found in the north Atlantic sediment cores which show poorly sorted, angular and contain rocks. These were originally in the icebergs but dropped to the bottom of the ocean when the icebergs melted.[1]
Heinrich events are a possible trigger to the onset of mini ice ages which follow a long period of thaw. An example might be the Younger Dryas, a brief cold period from about 12.8 thousand years ago to about 11.5 thousand years ago.[2][3]
The Younger Dryas stadial is thought to have been caused by the collapse of the North American ice sheets, although rival theories have been proposed.
Heinrich Event Media
The H1 Heinrich event occurred in the Pleistocene, around 16,000 years ago. Evolution of temperature in the Post-Glacial period since the Last Glacial Period, according to Greenland ice cores.
Chronology of climatic events of importance for the Last Glacial Period (~last 120 000 years) as recorded in polar ice cores, and approximate relative position of Heinrich events, initially recorded in marine sediment cores from the North Atlantic Ocean.
As well as indicating oceanic productivity, foraminifera tests also provide valuable isotopic data
The lithic proportion of sediments deposited during H3 and H6 is substantially below that of other Heinrich events
The ratio of calcium versus strontium (Ca/Sr) from a marine North Atlantic drill site (IODP U1308), that serves as a proxy for the mineralogically-distinctive "detrital carbonate" that characterizes Heinrich events is shown in blue (Hodell et al., 2008). Shown in red are petrologic counts of detrital carbonate over the last three glaciations (Bond et al., 1999; Obrochta et al., 2012, Obrochta et al., 2014) confirms that Ca/Sr is an indicator of Heinrich events.
Present-day ocean circulation. The Gulf Stream, far left, may be redirected during Heinrich events.
References
- ↑ Holden, J 2008. An Introduction to physical geography and the environment. 2nd ed. Essex: Pearson Education Limited. 576, 716.
- ↑ Berger, W. H. (1990). "The Younger Dryas cold spell — a quest for causes". Global and Planetary Change. 3 (3): 219–237. Bibcode:1990GPC.....3..219B. doi:10.1016/0921-8181(90)90018-8.
- ↑ Muscheler, Raimund; et al. (2008). "Tree rings and ice cores reveal 14C calibration uncertainties during the Younger Dryas". Nature Geoscience. 1 (4): 263–267. Bibcode:2008NatGe...1..263M. doi:10.1038/ngeo128.