March 3rd 2020

Predicting future sea-level


Field sampling involves collecting sediment cores from small lakes using various types of coring equipment. Here we see Anders Romundset and Thomas Lakeman getting ready for work on the island of Seiland (Finnmark, Norway). Photo: Lina Gislefoss/NGU.
NGU geoscientists will document past sea-level changes along the Norwegian coast, ranging from the end of the last Ice Age to the last few decades. In collaboration with the Norwegian Mapping Authority (Kartverket) and other researchers from Norway and Canada, the new results will help develop models that can forecast future sea-level changes in the coming centuries.

"The research directly addresses the impact of ongoing global climate change on society", say Thomas Lakeman (project leader) and Anders Romundset (researcher) with the Geological Survey of Norway. 

"When glaciers in Antarctica and Greenland melt, average global sea-level rises. The remaining questions, however, are where and how high does sea-level rise, and how vulnerable is the Norwegian coastline to predicted sea-level changes".  

Sea and land 

In cooperation with colleagues from several other institutions in Norway and Canada, NGU now leads this four-year research project funded by the Research Council of Norway. Over NOK 10 million have been allocated to resolve this complex scientific puzzle. 

Sea-level reconstructions and analyses will span the entire period after the last Ice Age, with emphasis on periods of rapid change, and when sea-levels were less stable. 

“Locally, shoreline displacements are the result of sea-level fluctuation and variations in continental uplift. The story is different for many sections of the Norwegian coast. The new project will attempt to uncover and understand the reasons for this variation," says Anders Romundset. 

Two researchers from NGU in yellow jackets are standing by a hole in the ice. A rope goes down into the icy water.
Fieldwork on lakes can also take place in the winter, as shown here at Snefjord (Finnmark; Norway). This year, fieldwork starts in the weeks before Easter. Photo: Anders Romundset. 

Coastal landscape 

Shoreline displacement is a fundamental aspect of Norwegian Quaternary geoscience and is central to the understanding of the Norwegian coastal landscape. Romundset reports that NGU has extensive experience with this type of research, but through this new project, researchers are making significant progress. 

Today, data from tide-monitoring stations and satellites show that sea-level rise is accelerating. 

It is not known precisely when the acceleration began or how much this acceleration exceeds the rate of coastal uplift in Norway. Sea level changes that have occurred during the last two to three thousand years will, therefore, be analyzed in detail and will be connected to instrumental records (ie. tide gauges).  

“Hopefully, we will discover new patterns and relationships between the variables. The new insights about past change will allow us to improve modelling tools for predicting how the shoreline will change in coming centuries," says Anders Romundset. 

Straight to the bottom 

"NGU's primary role in the project is to collect and interpret new field data from numerous sites nationwide. We have a unique natural setting to do this kind of work in Norway, with our craggy coastline in combination with substantial crustal uplift after the last Ice Age. Amongst the myriad hills and mountains stretching along and into the sea, lies many small lakes with magnificent geological archives preserved in their bottom sediments."

Romundset and Lakeman inform us that they will sample these paleoenvironmental archives by collecting sediment cores.  

The layering displayed in the samples serves as a natural archive of what has happened along Norway’s long stretches of coastline over thousands of years.

Romundset explains that from these samples, Norway’s geological history can be read like chapters in a book, revealing the timing of events. "Here we can take full advantage of these unique geological archives in a novel international collaboration with world-leading geophysicists, who will use our results to test and develop their advanced numerical models". 

Three researches take samples from a tidal desposit at Lista.
Here, the researchers take samples from tidal deposits at Lista, one of a few places along the Norwegian coast suspected of experiencing a marine transgression, i.e. relative to the land, sea-level is rising . Photo: Anders Romundset. 

Throughout Norway 

“Maybe we will need to change the models. After all, our field observations, provide us with the ‘answer sheet’," he points out. 

Extensive fieldwork begins in late winter in Finnmark, and the project will have activities both in Agder, along Western Norway and in Lofoten. 

NGU's partners in the project are the Norwegian Mapping Authority (Kartverket), the Norwegian University of Science and Technology (NTNU), the University of Bergen (UiB), Høgskulen in Western Norway (HVL), and the University of Ottawa and Memorial University in Canada. 

A core sample in a lab.
The core samples are studied in the laboratory. The layering of deposits can tell a lot about what has happened over time.  
Photo: Anders Romundset.