Wisconsinan Late-glacial environmental chage in Québec: A regional synthesis

A synthesis is presented of the evidence for regional deglaciation, lake sediment stratigraphy, vegetation history and climatic variations in Québec during that part of the Wisconsinan Late-glacial (12.5-9 ka BP) for which detailed records exist. Lake sediment data for all or part of this period are available from more than 125 lakes or bogs in the region. The information available indicates strong regional differentiation in climatic conditions, probably due to local effects close to the edge of the retreating Late Wisconsinan ice sheet. The Younger Dryas cooling is not evident in the data from Québec, but there appears to have been a strong climatic reversal during the early Holocene. Summary charts are presented of deglaciation and vegetation patterns in the region, but only qualitative assessments can be made of temperature variations.     

Correlation of Swedish glacial varves with the Greenland (GRIP) oxygen isotope record

A mean varve thickness curve has been constructed for a part of the Swedish varve chronology from the northwestern Baltic proper. The mean varve thickness curve has been correlated with the δ¹⁸O record from the GRIP ice-core using the Younger Dryas–Preboreal climate shift. This climate shift was defined by pollen analyses. The Scandinavian ice-sheet responded to a warming at the end of the Younger Dryas, ca. 10995 to 10700 clay-varve yr BP. Warming is recorded as a sequence of increasing mean varve thickness and ice-rafted debris suggesting intense calving of the ice front. The Younger Dryas–Preboreal climatic shift is dated to ca. 10650 clay-varve yr BP, about 40 yr after the final drainage of the Baltic Ice Lake. Both the pollen spectra and a drastic increase in varve thickness reflect this climatic shift. A climate deterioration, correlated with the Preboreal oscillation, is dated to ca. 10440 to 10320 clay-varve yr BP and coincides with the brackish water phase of the Yoldia Sea stage. The ages of the climatic oscillations at the Younger Dryas–Preboreal transition show an 875 yr discrepancy compared with the GRIP record, suggesting a large error in the Swedish varve chronology in the part younger than ca. 10300 clay-varve yr BP. Copyright © 1999 John Wiley & Sons, Ltd.     

The Weichselian Late-glacial in southwestern Europe (Iberian Peninsula,Pyrenees, Massif Central,northern Apennines)

This paper presents a summary of Late-glacial environmental changes in southwestern Europe (lberian Peninsula, Pyrenees, Massif Central and the northern Apennines). The emphasis is on palaeoclimatic interpretations inferred from key sites in the region from which the most detailed records are available and which have been radiocarbon dated. The earliest evidence for climatic improvement following the end of the last glacial stage is dated to ca. 15 ka BP and is found at a few sites only. By 13 ka BP, a more widespread and marked climatic improvement is evident, although it is difficult to be precise in the timing and magnitude of the event. There are significant variations in detail between the Late-glacial records, but evidence for a significant cooling correlated with the Younger Dryas event is widespread throughout the region. Just two sites in the region provide evidence for an earlier, less emphatic phase of climatic cooling, which is tentatively equated with the ‘Older Dryas’ of continental northern Europe. Dry conditions appear to have predominated throughout the region in the later part of the Younger Dryas and the early Holocene.     

早全新世降温事件的湖泊沉积证据

我国华北干旱－半干旱区封闭湖泊流域化学风化历史记录了全新世以来次级的气候环境波动过程。高精度的沉积物地球化学、物理及生物参数变化表明，在全新世早－中期过渡阶段存在一次强降温气候事件，具体表现为流域化学风化减弱（高Rb/Sr比）、湖泊产生力减弱（低有机碳）以及湖泊水位下降。虽然该事件的寒冷程度比Younger Dryas弱，但是其与来自湖沼（包括北极、非洲、北美、西欧、青藏高原、祁连山等）、海洋（比北大西洋、地中海、加勒比海等）、欧－美大陆生物组合、极地冰芯等在内的环境记录的冷事件发生时间基本一致，集中发生于8.0-8.5ka B.P.之间。     

Loess record of the Pleistocene–Holocene transition on the northern and central Great Plains, USA

Various lines of evidence support conflicting interpretations of the timing, abruptness, and nature of climate change in the Great Plains during the Pleistocene–Holocene transition. Loess deposits and paleosols on both the central and northern Great Plains provide a valuable record that can help address these issues. A synthesis of new and previously reported optical and radiocarbon ages indicates that the Brady Soil, which marks the boundary between late Pleistocene Peoria Loess and Holocene Bignell Loess, began forming after a reduction in the rate of Peoria Loess accumulation that most likely occurred between 13.5 and 15 cal ka. Brady Soil formation spanned all or part of the Bølling-Allerød episode (approximately 14.7–12.9 cal ka) and all of the Younger Dryas episode (12.9–11.5 cal ka) and extended at least 1000 years beyond the end of the Younger Dryas. The Brady Soil was buried by Bignell Loess sedimentation beginning around 10.5–9 cal ka, and continuing episodically through the Holocene. Evidence for a brief increase in loess influx during the Younger Dryas is noteworthy but very limited. Most late Quaternary loess accumulation in the central Great Plains was nonglacigenic and was under relatively direct climatic control. Thus, Brady Soil formation records climatic conditions that minimized eolian activity and allowed effective pedogenesis, probably through relatively high effective moisture.Optical dating of loess in North Dakota supports correlation of the Leonard Paleosol on the northern Great Plains with the Brady Soil. Thick loess in North Dakota was primarily derived from the Missouri River floodplain; thus, its stratigraphy may in part reflect glacial influence on the Missouri River. Nonetheless, the persistence of minimal loess accumulation and soil formation until 10 cal ka at our North Dakota study site is best explained by a prolonged interval of high effective moisture correlative with the conditions that favored Brady Soil formation. Burial of both the Brady Soil and the Leonard Paleosol by renewed loess influx probably represents eolian system response that occurred when gradual change toward a drier climate eventually crossed the threshold for eolian activity. Overall, the loess–paleosol sequences of the central and northern Great Plains record a broad peak of high effective moisture across the late Pleistocene to Holocene boundary, rather than well-defined climatic episodes corresponding to the Bølling-Allerød and Younger Dryas episodes in the North Atlantic region.     

Lateglacial and early Holocene summer temperatures in the southern Swiss Alps reconstructed using fossil chironomids

We present a Lateglacial and early Holocene chironomid‐based July air temperature reconstruction from Foppe (1470 m a.s.l.) in the Swiss Southern Alps. Our analysis suggests that chironomid assemblages have responded to major and minor climatic fluctuations during the past 17 000 years, such as the Oldest Dryas, the Younger Dryas and the Bølling/Allerød events in the Lateglacial and the Preboreal Oscillation at the beginning of the Holocene. Quantitative July air temperature estimates were produced by applying a combined Norwegian and Swiss temperature inference model consisting of 274 lakes to the fossil chironomid assemblages. The Foppe record infers average July air temperatures of ca. 9.9 °C during the Oldest Dryas, 12.2 °C during most of the Bølling/Allerød and 11.1 °C for the Younger Dryas. Mean July air temperatures during the Preboreal were 14 °C. Major temperature changes were observed at the Oldest Dryas/Bølling (+2.7 °C), the Allerød/Younger Dryas (?2 °C) and the Younger Dryas/Holocene transitions (+3.9 °C). The temperature reconstruction also shows centennial‐scale coolings of ca. 0.8–1.4 °C, which may be synchronous with the Aegelsee (Greenland Interstadial 1d) and the Preboreal Oscillations. A comparison of our results with other palaeoclimate records suggests noticeable temperature gradients across the Alps during the Lateglacial and early Holocene. Copyright © 2011 John Wiley & Sons, Ltd.     

Stable oxygen isotope and pollen records from eastern Scotland and a consideration of Late-glacial and early Holocene climate change for Europe

The presence of marl deposits belonging to the Lateglacial period in a former lake basin at Lundin Tower in Fife, Scotland has allowed palaeoenvironmental investigations by means of carbonate δ¹³C and δ¹⁸O, and organic matter δ¹³C, in addition to palynology. The variations that emerge reveal strong similarities between the pollen and isotope records and these are interpreted as reflecting climatic shifts. The classic Late-glacial pattern of Oldest Dryas–Bølling–Older Dryas–Allerød–Younger Dryas may be evident and other climatic oscillations are shown to have occurred not only during the Allerød but also in the Preboreal. The problem of the time discordance between isotopic change and pollen representation is addressed through explanations involving lags in plant colonization. A comparison of the δ¹⁸O records from 43 sites across Europe reveals two different regional patterns, which raises fundamental questions over the nature of Late-glacial palaeoclimates.     

Pollen-inferred Late-Glacial and Holocene climate in southern Balkans (Lake Maliq)

High-temporal resolution analysis of pollen records from Lake Maliq (Albania) provides quantitative estimates of monthly temperature and precipitation changes since the last deglaciation. The climate parameters were estimated using the best modern analogue technique with an updated modern pollen-climate database composed of 2748 surface samples. The record shows two main cooling phases in the Maliq area (the Oldest and Younger Dryas) and a cooling event around 8200 years, which suggests that the forcing factors driving climate variations in the North Atlantic area since the Last Glacial period also extended their influence into the Mediterranean area. The Oldest and Younger Dryas are also characterized by an arid climate and a change in the seasonality of precipitation: the summer precipitation tends to be greater during the cooling phases than during the temperate periods. The Holocene climate is relatively stable and the values of each parameter reach their modern levels, except for an arid event between 8300 and 8100 cal BP.     

Synchronization of late-glacial vegetation changes at Crystal Lake, Illinois, USA with the North Atlantic Event Stratigraphy

Late-glacial (17–11 cal ka BP) pollen records from midwestern North America show similar vegetation trends; however, poor dating resolution, wide-interval pollen counts, and variable sedimentation rates have prevented the direct correlation with the North Atlantic Event Stratigraphy as represented in the Greenland ice-core records, thus preventing the understanding of the teleconnections and mechanisms of late-Quaternary events in the Northern Hemisphere. The widespread occurrence of late-glacial vegetation and climates with no modern analogs also hinders late-glacial climate reconstructions. A high-resolution pollen record with a well-controlled age model from Crystal Lake in northeastern Illinois reveals vegetation and climate conditions during the late-glacial and early Holocene intervals. Late-glacial Crystal Lake pollen assemblages, dominated by Picea mariana and Fraxinus nigra with lesser amounts of Abies and Larix, suggest relatively wet climate despite fluctuations between colder and warmer temperatures. Vegetation changes at Crystal Lake are coeval with millennial-scale trends in the NGRIP ice-core record, but major shifts in vegetation at Crystal Lake lag the NGRIP record by 300–400 yr. This lag may be due to the proximity of the Laurentide ice sheet, the ice sheet's inherent slowness in response to rapid climate changes, and its effect on frontal boundary conditions and lake-effect temperatures.     

Tracking abrupt climate change in the Southern Hemisphere: a seismic stratigraphic study of Lago Cardiel, Argentina (49°S)

Lake sediments from a closed basin in southern Patagonia (Argentina) provide a continental archive with which to reconstruct climate change and to test the interhemispheric synchroneity of abrupt events. High-resolution sub-bottom seismic profiles of Lago Cardiel indicate substantial lake-level changes since the late Pleistocene, which were identified and dated in a series of long piston cores. These data allow the reconstruction of the regional water balance at 49=" PSFT − BC "202S since the late glacial. The seismic stratigraphy reveals a dry late glacial climate with a desiccation of the basin around 11 220 yr BP (¹⁴C). Lake level rapidly increased by 135 m at the Holocene transition. Following the early Holocene highstand at + 55 m, lake level never dropped significantly below modern level. The palaeoclimate changes implied by the Lago Cardiel record are out-of-phase with those implied by records from tropical South America and demonstrate considerable latitudinal asynchroneity in the climate evolution of this continent.     

Climatic oscillations in central Italy during the Last Glacial–Holocene transition: the record from Lake Accesa

This paper presents an event stratigraphy based on data documenting the history of vegetation cover, lake‐level changes and fire frequency, as well as volcanic eruptions, over the Last Glacial–early Holocene transition from a terrestrial sediment sequence recovered at Lake Accesa in Tuscany (north‐central Italy). On the basis of an age–depth model inferred from 13 radiocarbon dates and six tephra horizons, the Oldest Dryas–Bølling warming event was dated to ca. 14 560 cal. yr BP and the Younger Dryas event to ca. 12 700–11 650 cal. yr BP. Four sub‐millennial scale cooling phases were recognised from pollen data at ca. 14 300–14 200, 13 900–13 700, 13 400–13 100 and 11 350–11 150 cal. yr BP. The last three may be Mediterranean equivalents to the Older Dryas (GI‐1d), Intra‐Allerød (GI‐1b) and Preboreal Oscillation (PBO) cooling events defined from the GRIP ice‐core and indicate strong climatic linkages between the North Atlantic and Mediterranean areas during the last Termination. The first may correspond to Intra‐Bølling cold oscillations registered by various palaeoclimatic records in the North Atlantic region. The lake‐level record shows that the sub‐millennial scale climatic oscillations which punctuated the last deglaciation were associated in central Italy with different successive patterns of hydrological changes from the Bølling warming to the 8.2 ka cold reversal. Copyright © 2006 John Wiley & Sons, Ltd.     

Pollen‐ and diatom based environmental history since the Last Glacial Maximum from the Andean core Fúquene‐7, Colombia

The late Pleistocene–Holocene ecological and limnological history of Lake Fúquene (2580 m a.s.l.), in the Colombian Andes, is reconstructed on the basis of diatom, pollen and sediment analyses of the upper 7 m of the core Fúquene‐7. Time control is provided by 11 accelerator mass spectrometry (AMS) ¹⁴C dates ranging from 19 670 ± 240 to 6040 ± 60 yr BP. In this paper we present the evolution of the lake and its surroundings. Glacial times were cold and dry, lake‐levels were low and the area was surrounded by paramo and subparamo vegetation. Late‐glacial conditions were warm and humid. The El Abra Stadial, a Younger Dryas equivalent, is reflected by a gap in the sedimentary record, a consequence of the cessation of deposition owing to a drop in lake‐level. The early Holocene was warm and humid; at this time the lake reached its maximum extension and was surrounded by Andean forest. The onset of the drier climate prevailing today took place in the middle Holocene, a process that is reflected earlier in the diatom and sediment records than in the pollen records. In the late Holocene human activity reduced the forest and transformed the landscape. Climate patterns from the Late‐glacial and throughout the Holocene, as represented in our record, are similar to other records from Colombia and northern South America (the Caribbean, Venezuela and Panama) and suggest that the changes in lake‐level were the result of precipitation variations driven by latitudinal shifts of the Intertropical Convergence Zone. Copyright © 2003 John Wiley & Sons, Ltd.     

川北若尔盖高原红原泥炭剖面孢粉记录的晚冰期以来古气候古环境的演变

利用14C测年及孢粉分析方法对位于若尔盖高原的红原泥炭剖面进行了系统研究,重建了若尔盖地区晚冰期以来古环境的演化历史,并识别在此期间发生的主要气候事件.结果表明:该区晚冰期的气候特点为冷偏干或凉偏干,冷暖波动频繁.其中,14.1～13.4、12.4～12.0和10.5～10.0 kaBP之间的冷阶段分别对应于Oldest Dryas、Older Dryas及Younger Dryas事件;发生于12.6～12.4和12.0～10.5kaBP左右的暖阶段分别对应于Bolling及Allerod暖期.Younger Dryas事件之后,气候总体以温湿为主要特征,8.9～8.7和6.1～5.8kaBP之间的明显降温为全新世期间的2次冷事件.孢粉记录所反映的若尔盖地区晚冰期以来的气候演化与全球气候变化具有较好的可比性.     

Postglacial climate and vegetation history, north-central Kola Peninsula, Russia: pollen and diatom records from Lake Yarnyshnoe-3

A sediment core from Lake Yarnyshnoe-3 (69°04'N; 36°04'E), an emerged coastal lake from the tundra of the north-central Kola Peninsula, has been analyzed for fossil pollen and diatoms. The pollen record shows the Younger Dryas event marked by increasing Artemisia coupled with decreases in Poaceae, Cyperaceae and Salix at c. 10 700 to 10 000 BP. This core provides the first well-defined palynological record of the Younger Dryas event on the Kola Peninsula. Stomates from Pinus were recovered from the core interval between 8000 and 6000 BP. The stomates, coupled with elevated values of pine pollen, indicate that Pinus sylvestris grew near the arctic coastline of the central Kola Peninsula in the middle Holocene. However, the small number of stomates suggests that pines were not plentiful. The diatom record from the core reflects basin isolation from the sea and indicates additional limnological changes during the climate transition between c. 5000 and 4000 BP. The broadly similar climate and vegetation history on the north-central Kola Peninsula and in Fennoscandia demonstrates the propagation of late glacial and Holocene climate events from the North Atlantic region into the Eurasian Arctic.     

末次冰消期晚期青藏高原东北部气候变化

我国最大的内陆封闭湖泊青海湖的沉积岩芯为研究末次冰期/全新世过渡期间青藏高原东北部的环境变化和季风降水演变提供了连续高分辨率环境档案。对两孔岩芯的多学科研究结果表明:大约14000～11600aB.P.期间气候干冷,湖泊的自生碳酸盐和有机质生产率远低于全新世;季节性入湖径流量在11600aB.P.突然增大;从10700aB.P.起,夏季蒸发量突然增大,干旱化作用导致碳酸盐滩湖环境;区域降水量在10000aB.P.的增大结束了滩湖环境,标志了早全新世温暖较湿气候的开始。全新世早期的青海湖水深比现在要浅20m左右,表明那时的有效湿度显然比现在要低很多。14000～10000aB.P.期间青海湖水深不超过6m,说明在末次冰消期的这一时段中,青藏高原东北部没有形成大规模冰融水。在10700～10000aB.P.期间突发的干旱事件与西欧的新仙女木事件(YoungerDryas)年代相当,但没有气候变冷的证据。青藏高原东北部末次冰消期的气候变化表现了明显的阶段性特征和有效湿度的突然改变。区域季风降水量和夏季温度的变化决定了该过渡期的这种变化格局     

Precise radiocarbon dating of Late-Glacial cooling in mid-latitude South America

Variability of atmospheric ¹⁴C content often complicates radiocarbon-based chronologies; however, specific features such as periods of constant ¹⁴C age or steep changes in radiocarbon ages can be useful stratigraphic markers. The Younger Dryas event in the Northern Hemisphere is one of those periods, showing conspicuous ¹⁴C wiggles. Although the origin of those variations is not fully understood, we can make practical use of them and determine: (i) whether the Younger Dryas was global in extent; if so, (ii) were the initial cooling and the final warming synchronous worldwide; and (iii) what are the implications of these similarities/differences? Here we report high-resolution AMS ¹⁴C chronologies from the mid-latitudes of South America that pinpoint a cool episode between 11,400 and 10,200¹⁴C yr B.P. The onset of the final cool episode of the Late Glacial in the southern mid-latitudes, i.e., the Huelmo/Mascardi Cold Reversal, preceded the onset of the Younger Dryas cold event by ∼550 calendar years. Both events ended during a radiocarbon-age plateau at ∼10,200¹⁴C yr B.P. Thus, the Huelmo/Mascardi Cold Reversal encompasses the Younger Dryas, as well as a couple of short-term cool/warm oscillations that immediately preceded its onset in the North Atlantic region.     

Response of chironomids to Late Quaternary environmental change in the Taitao Peninsula,southern Chile

An Erratum has been published for this article in Journal of Quaternary Science 17(7) 2002, 721. There is conflicting evidence concerning the extent and timing of late Quaternary climate variability in southern South America and how this may be linked to climate change in the Northern Hemisphere. Critical unresolved questions include whether or not a cool period occurred in southern South America during the Younger Dryas Chronozone (YDC) (11 000–10 000 ¹⁴C yr BP; 13 000–11 200 yr BP), and the timing of wet and dry phases during the Holocene. To date most evidence is from glacial, pollen and beetle records but, in an attempt to resolve these questions, we have used chironomid midges as an independent proxy in one of the first studies of its kind in Patagonia. We investigated the dynamics of midge assemblages during the Late‐glacial and Holocene at Lago Stibnite on the Taitao Peninsula, southern Chile (46°S). Changes in the midge assemblage suggest that the climate may have become cooler and drier during the YDC. During the Holocene there were cyclical changes in the midge assemblage that may have been in response to trophic change and/or to changes in precipitation when conditions appear to have been drier than today at 9400–6300 ¹⁴C yr BP and 2400–1600 ¹⁴C yr BP. Copyright © 2002 John Wiley & Sons, Ltd.     

晚冰期以来月亮湖孢粉记录反映的古植被与古气候演化

地处季风/非季风影响过渡地带的月亮湖是大兴安岭中段阿尔山-柴河火山区中的一个火山口湖.其长8.86 m的沉积岩心孢粉记录, 揭示了末次冰期晚期以来的古植被演化和古气候变化历史: 20.9~18.0 cal. ka B.P.期间研究区的植被为典型草原, 气候寒冷干旱; 18.0~15.3 cal. ka B.P.期间研究区的植被为草甸草原, 气候寒冷湿润; 15.3~14.0 cal. ka B.P.期间乔木开始在当地发育, 植被开始由草甸草原向森林草原转变, 气候向较为温暖湿润的方向转变; 14.0~12.8 cal. ka B.P.期间森林草原在温暖湿润的气候影响下, 森林扩张, 草原退缩, 与B?lling-Aller?d暖期相对应; 12.8~11.8 cal. ka B.P.期间草原在寒冷气候下扩张, 可与新仙女木期相对应; 11.8~0.8 cal. ka B.P. 期间在较为温暖的气候条件下, 草原在气候快速变冷事件的影响下发生了多次扩张, 其中, 较为明显的6次气温突降事件分别发生在9.0~8.9, 8.2~7.8, 7.0~6.8, 6.1~5.6, 5.4~5.2, 2.3~1.8 cal. ka B.P..这些快速气候变化事件与全球和区域中其他高分辨率古气候记录具有可比性, 揭示出月亮湖敏感地记录了全球和区域气候的变化, 同时也表明研究区的高分辨率孢粉分析是研究东亚季风强度变化的良好指标.      

The impact of climate change on the bulk and clay geochemistry of fluvial residual channel infillings: the late Weichselian and Early Holocene River Meuse sediments (The Netherlands)

Fine-grained fluvial residual channel infillings are likely to reflect systematic compositional changes in response to climate change, owing to changing weathering and geomorphological conditions in the upstream drainage basin. Our research focuses on the bulk sediment and clay geochemistry, laser granulometry and clay mineralogy of Late-glacial and Early Holocene River Meuse (Maas) unexposed residual channel infillings in northern Limburg (The Netherlands). We demonstrate that residual channel infillings register a systematic bulk and clay compositional change related to climate change on a 1–10 k-yr time-scale. Late-glacial and Holocene climatic amelioration stabilised the landscape and facilitated prolonged and intense chemical weathering of phyllosilicates and clay minerals due to soil formation. Clay translocation and subsequent erosion of topsoils on Palaeozoic bedrock and loess deposits increased the supply of smectite and vermiculite within River Meuse sediments. Smectite plus vermiculite contents rose from 30–40% in the Pleniglacial to 60% in the Late Allerød and to 70–80% in the Holocene. Younger Dryas cooling and landscape instability caused almost immediate return to low smectite and vermiculite contents. Following an Early Holocene rise, within about 5000 yr, a steady state supply is reached before 5 ka (Mid-Holocene). Holocene sediments therefore contain higher amounts of clay that are richer in high-Al, low-K and low-Mg vermiculites and smectites compared with Late (Pleni-)glacial sediments. The importance of clay mineral provenance and loess admixture in the River Meuse fluvial sediments is discussed. © 1998 John Wiley & Sons, Ltd.     

A chironomid-based reconstruction of late glacial summer temperatures in the southern Carpathians (Romania)

Late glacial and early Holocene summer temperatures were reconstructed based on fossil chironomid assemblages at Lake Brazi (Retezat Mountains) with a joint Norwegian–Swiss transfer function, providing an important addition to the late glacial quantitative climate reconstructions from Europe. The pattern of the late glacial temperature changes in Lake Brazi show both similarities and some differences from the NGRIP δ¹⁸O record and other European chironomid-based reconstructions. Our reconstruction indicates that at Lake Brazi (1740 m a.s.l.) summer air temperature increased by ~ 2.8°C at the Oldest Dryas/Bølling transition (GS-2/GI-1) and reached 8.1–8.7°C during the late glacial interstade. The onset of the Younger Dryas (GS-1) was characterized by a weak (< 1°C) decrease in chironomid-inferred temperatures. Similarly, at the GS-1/Holocene transition no major changes in summer temperature were recorded. In the early Holocene, summer temperature increased in two steps and reached ~ 12.0–13.3°C during the Preboreal. Two short-term cold events were detected during the early Holocene between 11,480–11,390 and 10,350–10,190 cal yr BP. The first cooling coincides with the Preboreal oscillation and shows a weak (0.7°C) temperature decrease, while the second is characterized by 1°C cooling. Both cold events coincide with cooling events in the Greenland ice core records and other European temperature reconstructions.