Abstract
The subantarctic islands between 40 and 60°S are circum-polar landmasses influenced by the southern westerly wind (SWW) belt whose latitudinal shifts are driven by the Southern Annular Mode (SAM) over decadal timescales. In the Indian sector of the Southern Ocean, the Kerguelen Islands (49°S) form a volcanic archipelago that is home to the Cook Ice Cap (CIC). Atmospheric drying favored by a poleward migration of the SWW induced a dramatic shrinkage of the CIC over the past 50 years. Current knowledge of how this decline compares with the natural variability of the CIC is unclear and based exclusively on geomorphological records with limited temporal resolution. This paper introduces a 4 kyr marine record built from a transect of giant piston cores collected in Table Fjord, southwestern margin of the CIC. Interpretation of sedimentary and geochemical proxies is supported by statistical correlations with the CIC surface mass balance on the instrumental timescale, and by the age overlapping with dated landforms and deposits over the last two millennia. High-resolution geochronological data (137Cs and 210Pb inventories along with 63 AMS 14C dates) corrected from a local marine reservoir age allowed reconstructing glacier variability at a multidecadal resolution. The CIC was paced by periods of glacial advances at 3.4–2.8, 2.3–1.7, and 1.35–1.15 ka cal BP, followed by a two-stage ‘Little Ice Age’ maximum between 0.7 ka cal BP and the early 20th century. Comparison with paleoenvironmental records from the subantarctic fringe zone and the southern mid-latitudes suggests SWW-driven precipitation (wetter and windier conditions) were the main driver of centennial-scale glacier variability in the Kerguelen Islands, notably after 2.3 ka cal BP. The Kerguelen record thereby supports a zonally-synchronous, hemispheric-wide SWW pattern pacing Southern Ocean climatic variability in a SAM-like mode. The Little Ice Age maximum ice extent results from the coincidence of cold conditions caused by an equatorward shift of the Polar Front, an oceanic front bordering the Kerguelen archipelago resulting in lower sea surface temperatures, together with wetter conditions favored by strengthened SWW.
Original language | English |
---|---|
Article number | 108980 |
Pages (from-to) | 1-16 |
Number of pages | 16 |
Journal | Quaternary Science Reviews |
Volume | 344 |
Early online date | 28 Sept 2024 |
DOIs | |
Publication status | Published - 15 Nov 2024 |
Bibliographical note
Publisher Copyright:© 2024
Funding
The authors thank the M/D team members for the work during cruise missions, as well as IPEV and IFREMER for logistical and operational support. The authors thank the LMC14 (Laboratoire de Mesure du Carbone 14) staff, ARTEMIS national facility (LSCE (CNRS-CEA-UVSQ)-IRD-IRSN-MC) for the results obtained with the AMS method. Patrick Alb\u00E9ric (CNRS-ISTO) is thanked for Rock-Eval pyrolysis data. Xavier Crosta (CNRS-EPOC) is acknowledged for fruitful discussions on an early version of the manuscript. Special thanks are owed to Pierre Francus (INRS-ETE) and Patrick Lajeunesse (Universit\u00E9 Laval) for their financial support to LC during the writing process. The manuscript benefited from the comments of two anonymous reviewers and associate editor Giovanni Zanchetta.
Funders | Funder number |
---|---|
CNRS-ISTO | |
CNRS-EPOC | |
Institut français de recherche pour l'exploitation de la mer | |
CNRS-CEA-UVSQ | |
IRD-IRSN-MC | |
Institut Polaire Français Paul Emile Victor | |
Université Laval |
Keywords
- Glacial variability
- South Indian Ocean
- Southern Annular Mode
- Southern hemisphere
- Subantarctic fjord