Was there a ‘4.2 ka event’ in Great Britain and Ireland? Evidence from the peatland record

Abstract

palaeohydrological proxy data generated during this study (peat humification, plant macrofossil and testate amoebae analyses) supported by a high-resolution chronology (including comprehensive AMS 14 C and tephrochronology). The inter-site testate amoebae reconstructions appear coherent and were combined to produce a regional climatic record, in marked contrast to the plant macrofossil and peat 20 humification records that appear climatically complacent. The testate amoebae reconstruction, however, provides no compelling evidence for a 4.2 kyr event signal and is consistent with previously reported studies from across northwest Europe, suggesting the origin and impact of this event is spatially complex.

A 9000 year record of cyclic vegetation changes identified in a montane peatland deposit located in the Eastern Carpathians (Central-Eastern Europe): Autogenic succession or regional climatic influences?

“…4). The increase of E. vaginatum and a higher peat decomposition 3100-2700 may coincide with deterioration of climate during the 2.8 ka event documented based in a peat archive from NW Europe (Roland et al, 2014). It is worth emphasising that the increased values of Eriophorum vaginatum in five cases (ca.…”

“…Cooler and wetter conditions associated to the 4.2 kyr event (Mayewski et al, 2004) have been widely documented in the region by various records such as an increase of fluvial activity (Howard et al, 2014;Perşoiu, 2010), lake level rise Feurdean et al, 2013), oxygen isotopes (Perşoiu et al, 2010;Dragusin et al, 2014) and chironomid-based summer temperature reconstruction (Toth et al, 2015). However, wetter and cooler climatic conditions during 4.2 kyr event are not always clear and a lack of a coherent climatic response during the 4.2 kyr event was documented in peat archives from Great Britain and Ireland (Roland et al, 2014).…”

Formal subdivision of the Quaternary System/Period: Past, present, and future

“…In higher latitudes of the northern hemisphere and also in South America, it is often paradoxically expressed by cooler and/or wetter conditions (Roland, 2012;Roland et al, 2014), highlighting the complexity of processes responsible for this event.…”

An 8000-year multi-proxy peat-based palaeoclimate record from Newfoundland: Evidence of coherent changes in bog surface wetness and ocean circulation

“…Increased advection of cooler surface waters, driven by northerly winds from the Nordic and Labrador Seas, further south into the Atlantic is suggested by a fluctuating but overall increasing level of IRD (Figure 7a) from 7200-5500 BP in the Atlantic Ocean (Bond et al, 2001). In the eastern North Atlantic the importance of this period is clear; from the record of δ 13 CCalcite in benthic foraminifera (Oppo et al, 2003) 4200 BP (Bianchi and McCave, 1999) and evidence of increasing IRD c. 4800 BP to highs c. 4600 BP and c. 4200 BP exists (Bond et al, 2001) 4200 BP in the palaeoenvironmental literature are frequent (Mayewski et al, 2004;Booth et al, 2005), with drier conditions evident at mid-lower latitudes and some evidence of increased wetness in more northerly higher latitudes, although the latter appears to be less coherent (Roland et al, 2014). The period around 4200 BP is also often reported as the onset of neoglaciation in the Northern Atlantic region (Larsen et al, 2012;Balascio et al, 2015) as ice caps and glaciers re-advance.…”