From Greenhouse Gas to Carbonate Beneath the Seafloor

8 September 2025

The Maria S. MERIAN is setting sail for the Vøring Plateau off the coast of Norway. The expedition’s aim is to determine whether the basalt formations on the seabed are suitable for the long-term geological storage of CO2. (Image credit: Karen Hissmann, GEOMAR)

Limiting climate change will require, in addition to strong reductions of emissions, the removal and safe storage of large amounts of carbon dioxide from the atmosphere. One promising option for carbon capture and storage (CCS) lies beneath the seabed: in certain rocks known as basalts, CO2 could react naturally with water and rock to form carbonate minerals within just a few years, binding it permanently without the risk of leakage. Initial field trials in Iceland and the USA point in this direction. Could the widespread flood basalt formations along continental margins, therefore, play a role in future climate protection? That is what this expedition with Maria S. Merian will be investigating off the Norwegian coast.

CO2 Storage in Flood Basalts Beneath the Seabed

“Our central research question is: does the basalt below the seabed, in its properties and composition, have the potential to store CO2 permanently and safely?” explained Chief Scientist Dr. Ingo Klaucke, a geologist at the GEOMAR Helmholtz Centre for Ocean Research Kiel. The expedition will provide us with the necessary data to assess the storage potential of rocks and lay the foundation for their geophysical monitoring.”

The potential could be vast: globally, basalt deposits beneath the ocean theoretically have a storage capacity of 40,000 gigatons—several times the current annual global CO2 emissions. This is why the expedition is named “Permanent sequestration of gigatons of CO2 in continental margin basalt deposits, CO2PR.”

Extensive Lava Layers Off Norway’s Coast

The cruise will focus on the Skoll High on the Vøring Plateau off the Norwegian coast, where cores from previous scientific drilling expeditions have indicated extensive lava layers. To determine the properties of the seabed rock, the researchers will employ high-resolution 2D and 3D surveying techniques, including reflection and refraction seismic, as well as electromagnetic measurements. The resulting physical parameters, such as sound velocity and electrical resistivity, will then be fed into models to derive information on density and conductivity, and thus the rock’s storage potential. Artificial intelligence will support the data analysis. The aim is not only to identify suitable storage structures, but also to explore ways in which a future CO2 storage site could be monitored remotely—for example, using seismic or electromagnetic signatures that might indicate leaks.

When dissolved CO2 reacts with basalt rock, it can convert into a whitish carbonate, which is then fixed in the rock. (Image credit: Sandra Snaebjörnsdóttir, Carbfix)

En route to the study area, the team will deploy two ARGO floats northeast of Iceland to help close a gap in the ocean observation network.

Fewer Conflicts with Other Sea Uses

With its contribution to the international PERBAS initiative, Expedition MSM140 is providing important foundations for developing flood basalts as CO2 storage sites. In addition to their sheer size and the potentially rapid and permanent fixation rates, such sites have the advantage of usually being far offshore and therefore less intensively used than the North Sea or other shallow shelf seas. Conflicts with other forms of use will likely be less frequent. However, the great distance from the coast would make implementation costly, as tankers would need to transport CO2 far out to sea.