Tripartite climate reversal in Central Europe 5600–5300 years ago

Magny, Michel; Leuzinger, Urs; Bortenschlager, Sigmar; Haas, Jean Nicolas

doi:10.1016/j.yqres.2005.06.009

Cited by 144 publications

(115 citation statements)

References 95 publications

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“…6000 and 4500 cal BP, Ledro's flood frequency is relatively low, except for a few very thick deposits that are synchronous with a lakelevel rise around 5800-5300 cal BP. This coincides with a major worldwide cooling event (Magny et al, 2006). Figure 7 also shows similar increases in flood activity in the nearby Lake Iseo (50 km southwest of Lake Ledro; Lauterbach et al, 2012), in southern Italy (Piccarreta et al, 2011), in the Alps (Debret et al, 2010) and in Germany (Hoffmann et al, 2008).…”

Section: Variability In Flood Frequency In the Early To Mid-holocene supporting

confidence: 54%

Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern Italy

et al. 2013

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Abstract. Two lacustrine sediment cores from Lake Ledro in northern Italy were studied to produce chronologies of flood events for the past 10 000 yr. For this purpose, we have developed an automatic method that objectively identifies the sedimentary imprint of river floods in the downstream lake basin. The method was based on colour data extracted from processed core photographs, and the count data were analysed to capture the flood signal. Flood frequency and reconstructed sedimentary dynamics were compared with lake-level changes and pollen inferred vegetation dynamics. The results suggest a record marked by low flood frequency during the early and middle Holocene (10 000–4500 cal BP). Only modest increases during short intervals are recorded at ca. 8000, 7500, and 7100 cal BP. After 4500–4000 cal BP, the record shows a shift toward increased flood frequency. With the exception of two short intervals around 2900–2500 and 1800–1400 cal BP, which show a slightly reduced number of floods, the trend of increasing flood frequency prevailed until the 20th century, reaching a maximum between the 16th and the 19th centuries. Brief-flood frequency increases recorded during the early and middle Holocene can be attributed to cold climatic oscillations. On a centennial time scale, major changes in flood frequency, such as those observed after ca. 4500/4000 and 500 cal BP, can be attributed to large-scale climatic changes such as the Neo-glacial and Little Ice Age, which are under orbital and possibly solar control. However, in the Bronze Age and during the Middle Ages and modern times, forest clearing and land use probably partially control the flood activity.

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Section: Variability In Flood Frequency In the Early To Mid-holocene supporting

confidence: 54%

Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern Italy

et al. 2013

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“…6000-4000 cal BP (Magny et al, 2006b;Miller et al, 2010;Giraudi et al, 2011;Zanchetta et al, 2012;Vannière et al, 2012). These rapid climatic changes are recorded throughout the Mediterranean region, but their characteristic effects can vary spatially (e.g.…”

Section: Introductionmentioning

confidence: 99%

Climate and vegetation changes during the Lateglacial and early–middle Holocene at Lake Ledro (southern Alps, Italy)

et al. 2013

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Adding to the on-going debate regarding vegetation recolonisation (more particularly the timing) in Europe and climate change since the Lateglacial, this study investigates a long sediment core (LL081) from Lake Ledro (652 m a.s.l., southern Alps, Italy). Environmental changes were reconstructed using multiproxy analysis (pollen-based vegetation and climate reconstruction, lake levels, magnetic susceptibility and X-ray fluorescence (XRF) measurements) recorded climate and land-use changes during the Lateglacial and early–middle Holocene. The well-dated and high-resolution pollen record of Lake Ledro is compared with vegetation records from the southern and northern Alps to trace the history of tree species distribution. An altitude-dependent progressive time delay of the first continuous occurrence of Abies (fir) and of the Larix (larch) development has been observed since the Lateglacial in the southern Alps. This pattern suggests that the mid-altitude Lake Ledro area was not a refuge and that trees originated from lowlands or hilly areas (e.g. Euganean Hills) in northern Italy. Preboreal oscillations (ca. 11 000 cal BP), Boreal oscillations (ca. 10 200, 9300 cal BP) and the 8.2 kyr cold event suggest a centennial-scale climate forcing in the studied area. Picea (spruce) expansion occurred preferentially around 10 200 and 8200 cal BP in the south-eastern Alps, and therefore reflects the long-lasting cumulative effects of successive boreal and the 8.2 kyr cold event. The extension of Abies is contemporaneous with the 8.2 kyr event, but its development in the southern Alps benefits from the wettest interval 8200–7300 cal BP evidenced in high lake levels, flood activity and pollen-based climate reconstructions. Since ca. 7500 cal BP, a weak signal of pollen-based anthropogenic activities suggest weak human impact. The period between ca. 5700 and ca. 4100 cal BP is considered as a transition period to colder and wetter conditions (particularly during summers) that favoured a dense beech (Fagus) forest development which in return caused a distinctive yew (Taxus) decline. We conclude that climate was the dominant factor controlling vegetation changes and erosion processes during the early and middle Holocene (up to ca. 4100 cal BP)

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“…yr BP (Bonani et al, 1994;Baroni and Orombelli, 1996). Increased precipitation and lake-level highstands during these intervals and possible consequences for Neolithic lake dwellings have also been reported from other sites in Switzerland, Italy and France (Magny, 2004;Magny et al, 2006). Increased flood activity at Lake Mondsee between ca.…”

Section: Flood and Debris Flow Depositionmentioning

confidence: 74%

Late Neolithic Mondsee Culture in Austria: living on lakes and living with flood risk?

et al. 2013

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Neolithic and Bronze Age lake dwellings in the European Alps became recently protected under the UNESCO World Heritage. However, only little is known about the cultural history of the related pre-historic communities, their adaptation strategies to environmental changes and particularly about the almost synchronous decline of many of these settlements around the transition from the Late Neolithic to the Early Bronze Age. For example, there is an ongoing debate whether the abandonment of Late Neolithic lake dwellings at Lake Mondsee (Upper Austria) was caused by unfavourable climate conditions or a single catastrophic event. Within the varved sediments of Lake Mondsee, we investigated the occurrence of intercalated detrital layers from major floods and debris flows to unravel extreme surface runoff recurrence during the Neolithic settlement period. A combination of detailed sediment microfacies analysis and μXRF element scanning allows distinguishing debris flow and flood deposits. A total of 60 flood and 12 debris flow event layers was detected between 7000 and 4000 varve years (vyr) BP. Compared to the centennial- to millennial-scale average, a period of increased runoff event frequency can be identified between 5900 and 4450 vyr BP. Enhanced flood frequency is accompanied by predominantly siliciclastic sediment supply between ca. 5500 and 5000 vyr BP and enhanced dolomitic sediment supply between 4900 and 4500 vyr BP. A change in the location and the construction technique of the Neolithic lake dwellings at Lake Mondsee can be observed during the period of higher flood frequency. While lake dwellings of the first settlement period (ca. 5800–5250 cal. yr BP) were constructed directly on the wetlands, later constructions (ca. 5400–4700 cal. yr BP) were built on piles upon the water, possibly indicating an adaptation to either increased flood risk or a general increase of the lake level. However, our results also indicate that other than climatic factors (e.g. socio-economic changes) must have influenced the decline of the Mondsee Culture because flood activity generally decreased since 4450 vyr BP, but no new lake dwellings have been established thereafter

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Tripartite climate reversal in Central Europe 5600–5300 years ago

Cited by 144 publications

References 95 publications

Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern Italy

Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern Italy

Climate and vegetation changes during the Lateglacial and early–middle Holocene at Lake Ledro (southern Alps, Italy)

Late Neolithic Mondsee Culture in Austria: living on lakes and living with flood risk?

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