Radiocarbon Constraints on Periods of Positive Cave Ice Mass Balance During the Last Millennium, Julian Alps (Nw Slovenia)

Abstract

Caves containing perennial ice deposits make up a little-known, but emerging part of the cryosphere under increasing scrutiny from the scientific community. M-17, a sag-type ice cave opening at 1879 m asl in the Tolminski Migovec massif of the Julian Alps (NW Slovenia) contains a perennial underground ice deposit whose paleoclimate sensitivity is poorly understood and whose longevity under current climate change is at risk. The past mass balance of this cave is constrained using wood macro-remains embedded in ice. Accelerator mass spectrometry radiocarbon dating of 18 wood samples embedded in ice provides the largest currently available dataset for a subterranean ice deposit in the southern European Alps. The reconstructed chronostratigraphy reveals three main phases of likely positive ice balance around 900–1100 AD, 1200–1300 AD, and 1700–1800 AD, as well as a period of negative mass balance around 1300–1400 AD. The onset of cave glaciation is deemed to have occurred no later than about 900 AD, with evidence of overall positive ice mass balance during multi-decadal periods characterized by cooler-than-average summers and wetter-than-average springs. Conversely, negative mass balance is recorded during a period warmer-than-average summers and dry springs. The cave has experienced ice mass loss since its discovery in the 1980s.

First insights into the age of the giant ice deposits in the Eisriesenwelt cave (Austria)

“…These studies include the dating of plant remains or insects that passively or actively entered the cave and became embedded in the ice. Studies of ice stratigraphies in such sag-type caves in the Austrian 10 , 11 , Swiss 12 , 13 and Slovenian part 14 of the European Alps, the Spanish Pyrenees 15 , and Idaho, USA 16 , have revealed semi-continuous records spanning the second half of the Holocene. Occasionally, additional techniques such as tritium or 210 Pb have been used to constrain the age of the younger part of such ice deposits 12 , 17 .…”

Multi-centennial mass balance of perennial ice deposits in Alpine caves mirrors the evolution of glaciers during the Late Holocene

“…At Hundsalm Ice Cave, western Austria, periods of positive and negative mass balance were bracketed using a 19-sample radiocarbon dataset from wood inclusions 13 . Similarly, the timing and duration of ice deposition in a sag-type cave of the Julian Alps were constrained with the aid of an 18-sample dataset 29 . At Dobšínská cave in Slovakia, successive campaigns sampling the remains of bats embedded in the ice body helped constrain the age of the ice deposit to 2600 years 10 , 30 , 31 .…”

Mountain permafrost in the Central Pyrenees: insights from the Devaux ice cave

“…Ice caves are defined as cavities in rock hosting perennial ice that results from the transformation of snow and/or the freezing of infiltrating water reaching the cave (Perşoiu and Lauritzen, 2018). Cave ice can be dated and used as a valuable paleoclimate archive in non-polar areas (e.g., Stoffel et al, 2009;Spötl et al, 2013;Perșoiu et al, 2017;Kern et al, 2018;Sancho et al, 2018a;Leunda et al, 2019;Munroe, 2021;Racine et al, 2022). Furthermore, temporal and spatial changes in past permafrost distribution have been identified using speleothems (stalagmites, flowstones) in circumpolar and polar regions (e.g., Vaks et al, 2013Vaks et al, , 2020Moseley et al, 2021) as well as in mid-latitude regions (e.g., Lundberg and McFarlane, 2007;Fankhauser et al, 2016;Lechleitner et al, 2020).…”