Holocene climatic changes in the Kerguelen archipelago (South Indian Ocean) based on marine and lacustrine palaeoclimatic archives

2026

Article référencé dans le Web of Science WOS:001677684300001

Bellet E., Ménot G., Piot C., Crosta X., Grossi V., Sicre M. A., Mendez-Millan Mercedes, Klein V., Ansanay-Alex S., Makou M., Poulenard J., Malet E., Fanget B., Storen E., Leviavan N., Servettaz A., Bakke J., Sabatier P., Arnaud F.

Quaternary Science Reviews, 2026, 375, p. 109753 [19 p.] ISSN 0277-3791

Climatic variability in the Southern Hemisphere is largely controlled by the latitudinal position of the Southern Hemisphere Westerly Winds (SHW), whose migration influences precipitation, temperature, and Antarctic upwelling. This study presents the results of analyses of two lacustrine sediment cores from Lake Armor, located on the subantarctic Kerguelen Islands (49 degrees 15 ' S, 69 degrees 10 ' E), within the SHW belt. Lipid biomarkers (Glycerol Dialkyl Glycerol Tetraethers, n-alkanes, and their hydrogen isotopes) were used to reconstruct mean annual air temperature above freezing (MAF) and humidity conditions. These records are compared with a high-resolution diatom-based summer sea surface temperature (SST) reconstruction from marine core MD11-3353, situated 150 km southwest of Lake Armor. In the late glacial and Early Holocene, our results reveal a period of warm air temperature, comparable to current values and very warm sea surface temperature, 5 degrees C above the current values. Around 9000 cal a BP, an abrupt transition occurred, marked by a cooling of 5 degrees C in SST and 1.5 degrees C in MAF, interpreted as a northward migration of the SHW and associated oceanic fronts. The Mid-to-Late Holocene period is characterized by pronounced MAF variability, including a notably warm interval between 3000 and 2000 cal a BP, when n-alkane dD suggests the prevalence of wetter conditions. Since similar to 250 cal a BP, a southward migration of the SHW has produced a 2.5 degrees C rise in MAF. Our findings are overall consistent with previous studies from the Indian Ocean, but permit us to go a step further as by comparing SSTs and air temperatures. This suggests that SST is not a reliable predictor of air temperature on the Kerguelen Islands, particularly during the Early Holocene. We hence argue that Kerguelen air temperature is predominantly controlled by the position of westerly winds, as an indicator of reorganisations in air mass trajectories.

Sciences du milieu [021]

KERGUELEN ; OCEAN INDIEN

Fonds IRD [F B010096317]

fdi:010096317