Coastal consequences of a warming world: Utilizing climate-forced change of past polar shorelines to forecast future hazards

Coastal environments are particularly sensitive to climate change because the distribution of nearshore sediments is controlled by various climate-forced parameters, including global sea level, regional sedimentation, and local storms and floods. As a result, climate change may cause widespread coastal response in the form of shifting shoreline positions, changing coastal landscapes and habitat modification of ecosystems, potentially devastating to urban infrastructure, ecosystem services, societal economy and human health. The Intergovernmental Panel on Climate Change (IPCC) forecasts that rising temperatures, primarily driven by anthropogenic greenhouse-gas emissions, will lead to an accelerated rate of sea-level rise and hazardous storms and floods impacting the world’s coastlines during the 21st century and beyond. This poses an imminent challenge for human adaption, as outlined by the United Nations Sustainable Development Goals 9 and 13. This is particularly true for those societies urbanizing coastlines vulnerable to such changes, such as most of the coasts in Denmark. However, it remains uncertain how and how much coastal environments change with changing climate and temperatures in both time and space, mainly due to limited information from modern and historical data. Since approximately 40 % of the global population lives within 100 km of the shore, understanding coastal consequences of a warming world is crucial for forecasting future hazards.

This study will use an extraordinary data set from High-Arctic Svalbard of sedimentary archives of the geological epochs Paleocene and Eocene (66-34 million years old), because this time interval serves as one of the best possible analogs for the coming decades and centuries due to higher, but comparable, CO2 concentrations and temperatures than in modern times. This succession is globally unique because it contains abundant coal seams, representing fossil peat that both accumulated in a fine balance with the sea level and serves as a high-resolution archive of climate change. For this reason, the succession can be regarded as a full-scale natural laboratory for the study of coastal changes over time scales beyond human observation. To pursue this research target, the study will implement detailed sedimentological and geochemical analyses of the succession, both by fieldwork and virtual outcrop models of the world-class exposures in Svalbard and by available data from over 500 drill wells distributed across Spitsbergen (the largest island of Svalbard). Whereas precise mapping (which is of unprecedented detail) of shifts in sedimentary characteristics, environments, and coal layers will provide information on sea level changes, sampling of rocks in the field can be used to process direct climate proxies, including temperature.