Antarctic expedition searches for clues to future sea-level rise

Consequences for sea levels

“The East Antarctic Ice Sheet contains much of the Earth’s freshwater, so a potential future shrinking of the ice in a warming climate could have major consequences for global sea levels. We still don’t know very much about current melt patterns, but we intend to change that with this expedition to the Riiser-Larsen Ice Shelf,” says Arjen Stroeven, professor of physical geography at Stockholm University.

Manages remotely

Arjen Stroeven coordinates the expedition research theme, consisting of several independen research projects, remotely. However, two researchers from the Department of Physical Geography at Stockholm University will take part in the expedition, each heading two of the research areas:

• Ninis Rosqvist, professor of geography, leads a project focused on studying snow cores that reveal the annual snowfall of the ice sheet—similar to tree rings.
• Ian Brown, associate professor in Earth observation, leads a project that uses radar to collect data on the ice sheet’s volume and melt.

This year’s fieldwork

This year, thirteen researchers from several different countries are collecting field data both on the Riiser-Larsen Ice Shelf and in its drainage basin. The research results will later be published and compiled to support dialogue with policymakers.

Meteorological analyses from the region indicate that climate changes, but on-site observations are required to determine the extent of the development.

“There are indications from satellite data that snowfall is increasing, which may be a result of warmer air and ocean temperatures. But we still do not know how the ice sheet is responding, and therefore we cannot yet determine the rate at which sea levels will rise,” says Arjen Stroeven.

About Ninis Rosqvist’s research

“We will drill for snow cores—and for the first time we will be able to obtain results directly on-site. This is possible thanks to new equipment developed for Greenland by my Danish colleagues—so this will be the first time it is used in Antarctica,” says Ninis Rosqvist.

The research team aims to determine how much snow falls in the area each year; increased snowfall would indicate climate change.

“We will return to sites drilled in the 1980s. If we drill deep enough to reach snow layers from the 1980s, our goal is to obtain at least fifty years of data to observe long-term trends,” she continues.

Snow-based data

Unlike the Arctic, in East Antarctica snow and ice have not yet begun to melt. This means that snow and ice cores preserve an annual archive, much like tree rings. If the Antarctic atmosphere has warmed, the researchers will be able to detect it.

Together, the group, consisting of three researchers, will contribute new knowledge about the Antarctic atmosphere, ice, and ocean.

“Our starting point will be this year’s snow surface, and from there we will work downward and backward in time. We also want to understand spatial variation, so we will drill along a transect that begins on the floating Riiser-Larsen Ice Shelf near the ocean and ends on the Polar Plateau, more than 2,000 meters above sea level”, says Ninis Rosqvist.

The team also conducts measurements using ground-penetrating radar, which can detect layers in the snow between drilling locations.

“To obtain the spatial picture, we need samples from as many sites as possible.”

About Ian Brown’s research

Using satellite radar measurements, his team can detect cracks in the glacier, especially when they contain meltwater. The measurements can also show whether the ice sheet is gaining or losing mass—that is, whether, in the aggregate, it is shrinking or growing.

“By measuring the distance between the satellite and the ice surface with an altimeter, we can determine the surface elevation of the ice,” says Ian Brown.

Provides an overview

The method, called altimetry, uses an altimeter—an instrument that measures height above a reference level such as sea level. During an earlier expedition (2021/2022), Ian conducted preliminary work by measuring the microstructure of the snow and how it affects radar backscatter. With these field studies, the research team can build a complete picture of the ice sheet’s current state and reconstruct changes over the past 20 years.

“Changes in the Riiser-Larsen Ice Shelf are to be used as an early indicator of melting in Antarctica. If the ice shelf reaches a tipping point and begins to break apart, the situation could become serious. That would tell us that the changes have come to Dronning Maud Land,” says Ian Brown.