South Atlantic island record reveals a South Atlantic response to the 8.2 kyr event

Abstract

Abstract.One of the most distinct climate fluctuations during the Holocene is the short and rapid event centred around 8200 years ago, the 8.2 kyr event, which was most likely triggered by glacial melt-water forcing from the receding Laurentide ice-sheet. Evidence for this cooling has primarily been reported from sites around the North Atlantic, but an increasing number of observations imply a more widespread occurrence. Palaeoclimate archives from the Southern Hemisphere have hitherto failed to uncover a distinct climatic anomaly associated with the 8.2 kyr event. Here we present a lake sediment record from Nightingale Island in the central South Atlantic showing enhanced precipitation between 8275 and 8025 cal. yrs BP, most likely as a consequence of increased sea surface temperature (SST). We show that this is consistent with climate model projections of a warming of the South Atlantic in response to reduced north-ward energy transport during the 8.2 kyr event.

Formal subdivision of the Holocene Series/Epoch: a Discussion Paper by a Working Group of INTIMATE (Integration of ice‐core, marine and terrestrial records) and the Subcommission on Quaternary Stratigraphy (International Commission on Stratigraphy)

“…3), including cave speleothems in Oman, Yemen, China and Brazil (Fleitmann et al ., 2007; Cheng et al ., 2009); lake sequences in tropical Africa (Gasse, 2000) and the Tibetan Plateau (Zhang & Mischke, 2009); pollen records from the Mediterranean (Magri & Parra, 2002; Peyron et al ., 2011); ice cores from eastern Africa (Thompson et al ., 2002); pollen data from Siberia (Velichko et al ., 1997); and marine records from the north‐west Pacific (Hua et al ., 2008). In the South Atlantic, pollen and geochemical data from Nightingale Island in the Tristan da Cunha island group (Ljung et al ., 2007) suggest a short‐lived increase in precipitation that reflects either an intensification of the South Atlantic westerlies, or a sea surface temperature increase resulting from an Atlantic bipolar seesaw mechanism (Broecker, 1998). The latter is also indicated by coupled climate model simulations which show a warm response at around 8.2 ka BP in the South Atlantic and Southern Oceans (Wiersma et al ., 2011).…”

Early Holocene Laurentide Ice Sheet deglaciation causes cooling in the high-latitude Southern Hemisphere through oceanic teleconnection

“…Simulations of the 8.2 ka event show cooling in the North Atlantic region, followed after a few decades of warming in the South Atlantic Ocean [ Renssen et al , 2002; Wiersma and Renssen , 2006; LeGrande et al , 2006; Wiersma et al , 2008]. This model response has been corroborated by data from the South Atlantic region, showing evidence for a brief warm episode at the time of the North Atlantic cooling anomaly associated with the 8.2 ka event [ Ljung et al , 2007; Ljung and Björck , 2008].…”

Possible Late Pleistocene volcanic activity on Nightingale Island, South Atlantic Ocean, based on geoelectrical resistivity measurements, sediment corings and14C dating

“…1A) and at the northern rim of the Southern Hemisphere Westerlies (SHW) make them a perfect target for studies of paleoclimatic inter-hemispheric connections (Ljung & Björck 2007;Ljung et al 2008) and latitudinal changes of the SHW. During fieldwork in 2010, coring efforts were focused on NI with the aim to retrieve Late Pleistocene sediments for paleoclimatic studies of the Last Termination.…”