Arctic coastal areas can experience higher erosion rates than temperate regions due to the combined influence of seasonal permafrost melt and extreme temperatures. In addition to these ordinary dynamics, high latitude coastal areas are even more affected by climate-induced changes such as increased weather hazards, rising temperatures or changes in river discharges and sediment supply.

The Svalbard region consists of an archipelago of Arctic islands and a rocky and sandy coastline chiseled by numerous fjords connected to glaciers and a complex hydrographic network. Highly sensitive and exposed to the impacts of climate change, this coastal area is a perfect witness to the environmental changes of our century.

The Svalbard Archipelago has recently become a key hotspot with an increasing number of studies, mainly focusing on glacier melt, temperature change or soil destabilization. The environmental, geographical, and geomorphological conditions of Svalbard make it extremely difficult to monitor coastal change on a large-scale. However, several studies, including Lim et al. (2020), Jaskolski et al. (2018), and Sisneros-Kidd et al. (2019), have highlighted the strong pressure of climate change, population, and human activities on the Svalbard coastal area.

This littoral is fully in line with our approach to apprehend the past, present, and expected consequences of climate change on the environment and populations.

In close collaboration with local researcher Maria Jensen from the University of Svalbard (UNIS) and other experts in France (Agnès Baltzer and Franck Garestier), we have explored the potential of the Copernicus Programme satellite images to produce key information on the past and recent dynamics of nearly 300 km of coastline on the archipelago. This is a major challenge, given the complexity of the environment and the meteorological and climatic conditions of the region, which limit the volume of usable spatial data (cloud cover and seasonal ice on the monitored sediments).

After a first phase of adapting the algorithms to our developments, we extracted the coastline over 25 years, as well as the evolution of the banks and the extent of the hydrographic network along several major fjords in Svalbard. Particular attention was given to Advenfjorden to improve our effort, due to the greater availability of data to validate our results. We experienced the bathymetric monitoring into the fjord. This information was one of the most complex challenge in terms of methodology and algorithm development regarding the environmental context, but it is also a crucial insight to consider the full climate change impact on coastal sediment dynamics. Finally, we extracted another coastal indicator to focus on changes in the deltaic areas, namely the pioneer vegetation coverage, which reveals the impact of warming on these highly dynamic regions.

For the first time, we present our new results issued from these investigations.

Abstract. The EPICA Dome C (EDC) ice core provides the longest continuous climatic record covering the last 800 000 years (800 kyrs). Obtaining homogeneous high resolution measurements and accounting for diffusion provide a unique opportunity to study the evolution of decadal to millennial variability within the past glacial and interglacial periods. We present here a compilation of high resolution (11 cm) water isotopic records with 27 000 ?¹⁸O measurements and 7 920 ?D measurements (covering respectively 94 % and 27 % of the whole EDC record), including published and new measurements (2 900 for both ?¹⁸O and ?D) over the last 800 kyrs on the EDC ice core. We show that overlapping measurement series performed over multiple depth ranges over the past 20 years, using different analytical methods and in different laboratories, are consistent within analytical uncertainty, and therefore can be combined to provide a homogeneous data set. A frequency decomposition of the most complete ?¹⁸O record and a simple assessment of the possible influence of diffusion on the measured profile shows that the variability during glacial periods at multi-decadal to multi-centennial timescale is higher than variability of the interglacial periods. This analysis shows as well that during interglacial periods characterized by a temperature optimum at its beginning, the multi-centennial variability is the strongest over this temperature optimum.