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FRINATEK-Fri prosj.st. mat.,naturv.,tek

Quantifying past and future sea level changes in Norway

Alternative title: Kvantifisering av havnivåendringer langs norskekysten i fortid og framtid

Awarded: NOK 10.1 mill.

The QUANTSEA-project is improving century-scale sea-level projections for the Norwegian coast. Understanding future sea-level change in Norway requires estimates of future ice sheet melt and knowledge of future movements of Earth's crust. This project is collecting new observations of past sea level change, ranging from the last ice age to the last century, to improve our understanding of crustal motion. One dataset is being collected from lakes and bogs, which were connected to the sea thousands of years ago. A second dataset is being developed from salt marshes and lagoons in Agder, Rogaland, and Finnmark, which are sensitive recorders of recent sea-level changes (decades to millennia). Current research is aimed at narrowing the precision of sea level index points using state-of-the-art geochronology and sediment proxies (i.e., geochemistry, micropaleontology). Results from 2020-21 are included in a new database that is being used to develop new geophysical models that will improve sea-level forecasts for the next century and beyond. Geochemical and other proxy analyses of recent sea level trends (as well as analogous sea level changes during the early Holocene) is clarifying how sea-level rise will impact coastal environments. Understanding the impacts of sea-level rise and generating accurate forecasts of future sea-level change, will provide critical information for sustainable adaptation strategies to climate change.

Improving knowledge of the vulnerability of coastal Norway to future sea-level rise requires quantifying uncertainties in projected future sea surface heights and vertical land motions (derived from glacial isostatic adjustments (GIA)). The proposed research will use new, state-of-the-art GIA modelling to increase understanding of the magnitude and uncertainty of future vertical land motions across Norway, and to quantify and reduce uncertainty in century-scale relative sea-level (RSL) projections. The study aims to address significant knowledge gaps in past and present RSL change, which constitute critical benchmarks for the validation of state-of-the-art GIA models. Further, the research will explore former periods of RSL rise, i.e. paleo-analogues, in order to place the effects of anthropogenic climate change in a long-term context and to determine how future transgressions may impact coastal systems. Three Working Groups are proposed. Working Group 1 will determine the nature, rate, magnitude, and impact of recent RSL change (i.e. last two millennia) by integrating new proxy data collected from shallow marine areas and salt marshes with previously reported tide gauge records. Working Group 2 will develop new, high-resolution reconstructions of two enigmatic postglacial RSL transgressions in order to better understand former vertical land motions and the impact of past RSL rise on coastal systems. Working Group 3 will develop a GIA model based on a new RSL database generated by Working Groups 1 and 2, and will use the model to calculate present-day vertical land motion, better understand how GIA influences sea surface height, and reduce uncertainty in RSL projections along the Norwegian coast over the next century and beyond. Results from the proposed research will quantify knowledge of climate change impacts on coastal Norway and Fennoscandia, and will contribute to the development of sustainable adaptation strategies.

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FRINATEK-Fri prosj.st. mat.,naturv.,tek