Sea–level changes during the Miocene Icehouse Earth under high atmospheric CO2

Fossil fuel consumption over the last century has resulted in a drastic increase in atmospheric carbon dioxide (ρC02) from pre-industrial levels of ~280 ppm, to over 400 ppm in September 2018 – values not exceeded for millions of years. According to IPPC the increased CO2 have impact not only on temperatures but also on the sea-level. It is estimated that by the end of this century the sea-level will have increased up to 100 cm. The low topography and long coastline makes Denmark especially sensitive to even minor sea-level changes.

The purpose of the project is to evaluate the temperature changes and sea-level rise in the North Sea Basin under higher-than-present atmospheric CO2. To achieve the goal the research team will perform multidisciplinary (e.g. dinocysts, pollen, isotopes, biomarkers, seismic, etc) high-resolution analysis of the sediment core from the Sdr. Vium borehole, located near Ringkøbing in the western part of Jylland. The borehole penetrated an almost complete Miocene succession (21 to ~9 Million years ago).

Studying the Miocene epoch is particularly valuable for understanding the effects of global climate changes under elevated ρC02.for a number of reasons. The significant, global warming event called the Middle Miocene Climatic Optimum (MMCO; 17-14 Million years ago), is the last period in the Earth’s history with ρC02 levels similar to the values predicted for the coming millennium (i.e. 400–600 ppm).

The results obtained within SealMICO2 will be fundamental for the future numerical modelling of the Miocene deltaic systems in order to map the lithological distribution for hydrological flow models. It is important for e.g. enhanced drinking water recovery and for hot water storage. The results will complement the understanding of the impact of high CO2 concentrations on air and ocean/sea temperatures in the North Atlantic region and the interplay between the CO2 values and sea-level changes in the North Sea Basin. This is highly relevant for improving future climate predictions and aid the UN SDG13-Climate Action.