A 1500-years record of North Atlantic storminess from the Shetland Islands (UK)

Abstract

Abstract Severe storm surges pose a major hazard to the coasts of northwestern Europe. Therefore, high-resolution records of past North Atlantic storminess are required to assess (i) whether storm activity has increased in recent decades and (ii) which future risks may arise from storm surges. This study aims to decipher storm-induced overwash processes in lacustrine sediment cores from a coastal lake on the Shetland Islands by investigating distinct sand and peat layers. This multi-proxy study utilises a range of methods such as; Bayesian AMS-14C and 137Cs age-depth models, cryptotephra, sedimentological, and geochemical (i.e., XRF, TOC) analyses, and the re-analysis of historical data. The XRF Si/Ti ratio and the unimodal grain-size distribution clearly show that the sand layers originate from the beach and thus are representative of storms originating from a northwesterly direction. Phases of higher storminess occurred 980–1050, 1150–1300, 1450–1550, 1820–1900 and 1950–2000 AD which correlate with a positive North Atlantic Oscillation mode enhancing water inflow into the Norwegian Sea. High-intensity storms from other directions than north(west) and a southward shift of storm tracks prevailed during the Little Ice Age (LIA, 1400–1850 AD). During warm phases of the last 1500 years, storm tracks have shifted towards the northeast Atlantic, thus confirming a possible trend for future storm track changes and increased storminess in the northern region of the North Sea as predicted by the Intergovernmental Panel on Climate Change (IPCC).