Solar and proxy-sensitivity imprints on paleohydrological records for the last millennium in west-central Europe

International audienceThis paper presents a lake-level record established for the last millennium at Lake Saint-Point in the French Jura Mountains. A comparison of this lake-level record with a solar irradiance record supports the hypothesis of a solar forcing of variations in the hydrological cycle linked to climatic oscillations over the last millennium in west-central Europe, with higher lake levels during the solar minimums of Oort (around AD 1060), Wolf (around AD 1320), Spörer (around AD 1450), Maunder (around AD 1690), and Dalton (around AD 1820). Further comparisons of the Saint-Point record with the fluctuations of the Great Aletsch Glacier (Swiss Alps) and a record of Rhône River floods from Lake Bourget (French Alps) give evidence of possible imprints of proxy sensitivity on reconstructed paleohydrological records. In particular, the Great Aletsch record shows an increasing glacier mass from AD 1350 to 1850, suggesting a cumulative effect of the Little Ice Age cooling and/or a possible reflection of a millennial-scale general cooling until the mid-19th century in the Northern Hemisphere. In contrast, the Saint-Point and Bourget records show a general trend toward a decrease in lake levels and in flood magnitude anti-correlated with generally increasing solar irradiance

Standardization of double blind placebo controlled food challenge with soy within a multicentre trial

Background: Multicentre trials investigating food allergies by double blind placebo controlled food challenges (DBPCFC) need standardized procedures, challenge meals and evaluation criteria. We aimed at developing a standardized approach for identifying patients with birch related soy allergy by means of DBPCFC to soy, including determination of threshold levels, in a multicentre setting. Methods: Microbiologically stable soy challenge meals were composed of protein isolate with consistent Gly m 4 levels. Patients sensitized to main birch allergen Bet v 1 and concomitant sensitization to its soy homologue Gly m 4 underwent DBPCFC. Outcome was defined according to presence and/or absence of ten objective signs and intensity of eight subjective symptoms as measured by visual analogue scale (VAS). Results: 138 adult subjects (63.8% female, mean age 38 years) underwent DBPCFC. Challenge meals and defined evaluation criteria showed good applicability in all centres involved. 45.7% presented with objective signs and 65.2% with subjective symptoms at soy challenge. Placebo challenge meals elicited non-cardiovascular objective signs in 11.6%. In 82 (59.4%) subjects DBPCFC was judged as positive. 70.7% of DPBCFC+ showed objective signs and 85.4% subjective symptoms at soy challenge. Subjective symptoms to soy challenge meal in DBPCFC+ subjects started at significantly lower dose levels than objective signs (p < 0.001). Median cumulative eliciting doses for first objective signs in DBPCFC+ subjects were 4.7 g [0.7–24.7] and 0.7 g [0.2–4.7] total soy protein for first subjective symptoms (p = 0.01). Conclusions: We present the hitherto largest group of adults with Bet v 1 and Gly m 4 sensitization being investigated by DBPCFC. In this type of food allergy evaluation of DBPCFC outcome should not only include monitoring of objective signs but also scoring of subjective symptoms. Our data may contribute to standardize DBPCFC in pollen-related food allergy in multicentre settings. Trial registration EudraCT: 2009-011737-27

Beitrag zur Geschichte des Grossen Aletschgletschers

No abstract available

Neue Ergebnisse zur Gletscher- und Klimageschichte des Spätmittelalters und der Neuzeit

This article contributes to the glacier and climatic fluctuations during the late Middle Ages and the Modern Times. With the aid of radiocarbon dating of fossil woods and a fossil soil (fAh) located in the gletschervorfeld of two glaciers (Glacier de Zinal and Riedgletscher, Valais), the foUowing glacier advances could be shown: between 890 yBP and 1095 yBP, at 515 yBP, in the seventeenth and in the nineteenth Century. The tree rings from a larch (Larix decidua Mill.) near the glacier and the tree line (Riedgletscher, 2180 m altitude) was analysed by the X-ray densitometry. The maximum density of the annual rings reflects the summer temperatures since the middle of the twelfth Century. The fluctuations of the maximum density shows a close interrelation with the fluctuations of the Grosser Aletschgletscher (Valais). The local climatic influence of the Riedgletscher during maximal extension is visible in reduced tree-growth. During the retreat phase, when the glacier melted back, the regional climate dominates the tree-growth again

Neuzeitliche Gletscherschwankungen

No abstract available

Rekonstruktion von Gletscherschwankungen mit Hilfe fossiler Hölzer

Im vorliegenden Artikel wird gezeigt, wie mit Hilfe von fossilen Hölzern aus dem Gletschervorfeld minimale Gletscherausdehnungen und Gletschervorstöße erfaßt werden können. Einige zeitgenössische Berichte und Zeichnungen aus der Zeit um 1850, als die Alpengletscher ihren letzten neuzeitlichen Hochstand erreichten, sollen veranschaulichen, wie Gletscher in bewaldetes Gebiet vordrangen und Bäume umdrückten. Es wird im weiteren kurz auf die Lage von fossilem Holz im Gletschervorfeld und auf ihre wichtigsten Merkmale (guter Erhaltungszustand, Verengung der peripheren Jahrringe, Gletscherschlifl) eingegangen. Ein konstruierter Modellfall veranschaulicht, wie fossiles Holz in situ gletschergeschichtlich ausgewertet werden kann. Als praktisches Beispiel dazu werden die Schwankungen des Großen Aletschgletschers seit 1400 yBP erläutert. Zum ersten Mal überhaupt konnten an einem Gletscher mittelalterliche Gletschervorstöße anhand dendrochronologisch absolut datierter Hölzer jahrgenau erfaßt werden. Ebenso kann mittels solch absoluter Datierungen die Vorstoßphase des Großen Aletschgletschers von 1588 bis 1653 relativ detailliert erfaßt werden

The 10Be deglaciation chronology of the Göschenertal, central Swiss Alps, and new insights into the Göschenen Cold Phases

The Göschenertal (Göschenen valley) is the type locality of the so‐called Göschenen Cold Phases I (~3–2.3 ka) and II (~1.8–1.1 ka). According to earlier studies, these Late Holocene climatic cooling periods were characterized by changes in vegetation and pronounced glacier advances. As a peculiarity, the Göschenen Cold Phase I was thought to be connected to a local surge‐type advance of the Chelengletscher (Chelen glacier) – an exceptional event of unparalleled dimension in the European Alps. Based on cosmogenic 10Be exposure ages from moraine boulders, we investigated the local glacier chronology. In contrast to former research, moraines at different positions within the Göschenen valley (central Swiss Alps) have been dated to the Younger Dryas and the Early Holocene. This questions the applicability of palaeo‐Equilibrium Line Altitude (ELA) calculations for stadial attributions without additional numerical age constraints. Furthermore, we have found compelling evidence that the proposed non‐climatic glacier advance attributed to the Göschenen Cold Phase I did not occur. The present results, along with a reappraisal of the original study, question the scientific reliability and the glaciological definition of the Göschenen Cold Phases as glacier advances that clearly exceeded the Little Ice Age positions. While our data do not exclude potential changes in climate and vegetation, we nonetheless show that the Göschenen Cold Phases are not suitable as reference stadials in the system of Alpine Holocene glacier fluctuations