Article

Centennial-scale climate cooling with a sudden cold event around 8.200 years ago. Nature 434: 975-979

Southampton Oceanography Centre, Southampton SO14 3ZH, UK.
Nature (Impact Factor: 41.46). 05/2005; 434(7036):975-9. DOI: 10.1038/nature03421
Source: PubMed

ABSTRACT

The extent of climate variability during the current interglacial period, the Holocene, is still debated. Temperature records derived from central Greenland ice cores show one significant temperature anomaly between 8,200 and 8,100 years ago, which is often attributed to a meltwater outflow into the North Atlantic Ocean and a slowdown of North Atlantic Deep Water formation--this anomaly provides an opportunity to study such processes with relevance to present-day freshening of the North Atlantic. Anomalies in climate proxy records from locations around the globe are often correlated with this sharp event in Greenland. But the anomalies in many of these records span 400 to 600 years, start from about 8,600 years ago and form part of a repeating pattern within the Holocene. More sudden climate changes around 8,200 years ago appear superimposed on this longer-term cooling. The compounded nature of the signals implies that far-field climate anomalies around 8,200 years ago cannot be used in a straightforward manner to assess the impact of a slowdown of North Atlantic Deep Water formation, and the geographical extent of the rapid cooling event 8,200 years ago remains to be determined.

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    • "Within the same time interval, increased abundance of G. bulloides, higher δ 13 C G. bulloides values, and positive shifts in marine algal biomarkers (Figs. 6, 7, 8b) suggest enhanced productivity in the water column. The associated lower SSTs at ~8.2 ka (Fig. 8a) add evidence to an abrupt SST minimum related to the cold B8.2 ka^ event (Rohling and Pälike 2005; Marino et al. 2009; Rohling et al. 2015). 8.0–7.7 ka (interruption of sapropelic deposition) The recorded interruption of S1 at ~8.0 ka in the south Limnos Basin M4-G core features cooler conditions in the water column as indicated by alkenone-based SSTs (minimum at 7.8 ka; Fig. 8a), and the shift of δO 18 G. bulloides records toward larger values (Fig. 8c); the latter could also be related to freshwater inflow. "
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    • "According to Richard Tipping et al. (2012) the old paradigm of slow, gradual change (Lamb 1977; 1995) has been replaced by one in which change can be described as abrupt, occurring over short timescales of centuries or less, separated by comparatively long periods of quasi-stasis (Mayewski et al. 2004). The 8.2ka years event was part of a climatic cooling period from c. 8600 to 8000 calBP (Rohling, Pälike 2005; Thomas et al. 2007; Walker et al. 2012) that interrupted the long-term trend of rising early- Holocene temperatures. The event lasted approx. "
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