KALEHO (LEFE)

Understanding the mechanisms of global warming and its impact on human societies is one of the major challenges of the 21st century. In this context glaciers are excellent indicators of climate because their development depends directly on atmospheric conditions in terms of temperature and precipitation. Like most of the world's glaciers, the sub-Antarctic glaciers are currently undergoing a marked retreat. In the Kerguelen Islands (49 ̊S, 69 ̊E), the Cook Cap has undergone very significant and extremely rapid retreat, losing 20% of its surface area in 40 years, associated with values of one of the most negative mass balances observed worldwide. These current record values seem exceptional, but are they really so in view of the past glacial evolutions ? Does the current downturn correspond to natural variability, or is it a marker of the emergence of anthropogenic climate change? in Kerguelen? Ultimately, what can these observations tell us about thefuture glacial evolution of these regions and the iPotential impact on Southern Ocean fertilisation ? To answer these questions, we first need to look at thepast evolution of austral glaciersfor which the influence of man is considered negligible. The Kerguelen Islands, by virtue of their geographical location and history, constitute a exemplary case to understand past climate mechanisms in the Indian Ocean. In fact, apart from southern Patagonia, Kerguelen is the only sub-Antarctic archipelago with a high level ofwell-preserved ancient land ducts to document the past evolution of glaciers and associated regional climate change for over 21,000 years.

The overall aim of KALEHO is to trace the evolution of glaciers in the Kerguelen archipelago during the Holocene, in order to understand the climatic mechanisms at work in this southern region of the Indian Ocean over the last 11,000 years. To do this, we will first refine the chronology of glacial paleostates on the archipelago thanks to the dating of new palaeo-glacio-geomorphological samples collected around the Cook Cap and on the Rallier du Baty Peninsula, located to the south-west of the archipelago.