Lake-Level fluctuations at Le Locle, Swiss Jura, from the Younger Dryas to the Mid-Holocene: A high-resolution record of climate oscillations during the final deglaciation

Abstract

On the basis of a high-resolution (10 cm / 110 years) lacustrine sequence from Le Locle, Swiss Jura, a fine-scale pattern of palaeohydrological changes is reconstructed for the late Younger Dryas (YD) and the early to mid-Holocene period. The late YD is characterized by a general trend of a fall in lake level and a large climatic instability. The early to mid-Holocene period shows a quasi-cyclic pattern of lake-level fluctuations. Large drops in lake level occurred at ca. 11 600-10 200 cal. BP and ca. 8 900-7 700 cal. BP. Each was interrupted by a short-term rise in lake-level and followed by a longer phase of high lake level respectively at ca. 10 200-8 900 cal. BP and ca. 7 700-6 600 cal. BP. The high lake-level periods at le Locle appear to be in phase with cold spells reconstructed in central Europe, in eastern North America and in the Greenland ice-sheet, or with cooling events and salinity anomalies recorded in the North Atlantic zone. They also coincide with rising residual Δ14C values. These data and the Lateglacial oxygen-isotope GISP2 record suggest three successive quasi-cycles of climatic and environmental changes showing strong similarities in their internal structure. These cycles suggest that large-scale climate oscillations developing from the Bølling warming to the mid-Holocene could have been associated with changes in ocean ventilation probably induced by three deglaciation steps. Finally, as a working hypothesis, a re-exami- nation of the YD event is proposed from a Holocene point of view.

Holocene vegetation and land‐use changes in response to climatic changes in the forelands of the southwestern Alps, Italy

“…It is unlikely that temperature changes could have led to failure in crop harvest at this altitude in the forelands of the Alps . Instrumental data, glacier oscillations, and reconstructions of lake-level changes show that cooling events in the Alps were associated with increased summer precipitation (Magny and Schoellammer, 1999;Wanner et al, 2000;Magny et al, 2003b;Magny, 2004). Rainy summers can have a negative influence on cereal crop yields, for cereal plants are adapted to the dry climatic conditions of the Near East (Wright and Thorpe, 2004).…”

Future Climate Impacts in Woodland and Forest Steppe Based on Holocene Paleoclimatic Trends, Paleobotanical Change in Central Part of the Carpathian Basin (Hungary)

“…At 6000 cal. BP a high lake-level phase of Swiss lakes [74,75] and changes in the moisture gradient of some British peatlands [15] point to the emergence of cooler conditions. Similarly at 3500 cal.…”

Persistent millennial-scale shifts in moisture regimes in western Canada during the past six millennia

“…For example, syntheses of flood records from the U.S. Southwest (8,9) and the Upper Mississippi Valley (10) suggest that major changes in precipitation regimes have occurred on a millennial scale for at least the past 7,000 years. Millennial-scale fluctuations during the Holocene have been inferred in the Jura and French subalpine regions (11,12) based on composite records of changes in lake level; however, these records are dominated by large variations at the centennial to multicentennial scales rather than at the millennial. Similarly, the few higher-resolution records from western North America exhibit predominantly decadal to multicentennial variations (13).…”