New glacier evidence for ice-free summits during the life of the Tyrolean Iceman

Abstract

Detailed knowledge of Holocene climate and glaciers dynamics is essential for sustainable development in warming mountain regions. Yet information about Holocene glacier coverage in the Alps before the Little Ice Age stems mostly from studying advances of glacier tongues at lower elevations. Here we present a new approach to reconstructing past glacier low stands and ice-free conditions by assessing and dating the oldest ice preserved at high elevations. A previously unexplored ice dome at Weißseespitze summit (3500 m), near where the “Tyrolean Iceman” was found, offers almost ideal conditions for preserving the original ice formed at the site. The glaciological settings and state-of-the-art micro-radiocarbon age constraints indicate that the summit has been glaciated for about 5900 years. In combination with known maximum ages of other high Alpine glaciers, we present evidence for an elevation gradient of neoglaciation onset. It reveals that in the Alps only the highest elevation sites remained ice-covered throughout the Holocene. Just before the life of the Iceman, high Alpine summits were emerging from nearly ice-free conditions, during the start of a Mid-Holocene neoglaciation. We demonstrate that, under specific circumstances, the old ice at the base of high Alpine glaciers is a sensitive archive of glacier change. However, under current melt rates the archive at Weißseespitze and at similar locations will be lost within the next two decades.

Hidden paleosols on a high-elevation Alpine plateau (NW Italy): Evidence for Lateglacial Nunatak?

“…In this period a ~3-4 °C temperature increase was estimated with respect to the Younger Dryas (e.g., Tinner and Kaltenrieder, 2005;Ilyashuk et al, 2009;Larocque-Tobler et al, 2010;Samartin et al, 2012b). Glaciers were probably smaller than present day during the height of the HCO (e.g., Ivy-Ochs et al, 2009;Orombelli, 2011;Grämiger et al, 2018;Bohleber et al, 2020). Mean air temperature was up to 1-2 °C warmer with respect to the present-day values in the European Alps (e.g., Grove, 1988;Nesje and Dahl, 1993;Antonioli et al, 2000;Ivy-Ochs et al, 2009) and the inferred July temperature at the Plateau may have reached values around 6-7 °C (or even more) (cf.…”

Deciphering the evolution of the Bleis Marscha rock glacier (Val d'Err, eastern Switzerland) with cosmogenic nuclide exposure dating, aerial image correlation, and finite element modeling

“…By examining the exposure ages and considering the image correlation and FE modeling results, we decipher the history of the Bleis Marscha rock glacier over the past 9 kyr and put it into the framework of the known regional climate history (Ivy-Ochs et al, 2009;Böhlert et al, 2011a).…”

Reconstruction of the Interannual to Millennial Scale Patterns of the Global Surface Temperature

“…A significant mismatch between climate model predictions and data has also been observed throughout the Holocene (during the last 10,000 year) where climate models simulate continuous global warming, mainly in response to rising CO 2 and the retreat of ice sheets, while marine and terrestrial proxy records suggest global cooling during the Late Holocene, following the peak warming of the Holocene Thermal Maximum (from about 10,000 to 6000 year ago) [30,31]. Indeed, according to Milanković theory, the Earth's climate should be approaching the next ice age due to astronomical orbital oscillations [32] although the exact involved physical mechanisms are still unknown.…”