Future global warming will have a tremendous impact on coastal marine ecosystems. These changes will be particularly dramatic in the sub-Arctic and Arctic regions, which have experienced similar conditions during different warm periods in the past (e.g., Holocene Optimum, mid-Pliocene Warm Period). Modern weather records often just date back to the past 150 years or less. However, this is far too short to reveal long-term climate signals. Because of their longevity, some bivalves can record their surrounding environment for centuries. Information about palaeo-environmental and palaeo-climatic conditions is stored within the shell in different ways: the relative growth increment width, the isotopic composition and the crystal fabric of the skeletal hard parts. By applying sclerochronological techniques, a great variety of information can be revealed. Fossil shells of Arctica islandica from Spitsbergen (Dicksonfjorden; Holocene Optimum) were analysed for their potential to reconstruct local environmental conditions approximately 9000 years ago. Here we present first results on the state of preservation of these shells and first evidence for decadal oscillations (e.g., ENSO or NAO like patterns) in growth during the Holocene Optimum.