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  • Writer's pictureCoraline Leseurre

GreenFeedBack: A project to trace greenhouse gas dynamics in the Arctic Ocean

This summer, a team of five Belgian scientists embarked aboard the new research vessel Belgica in order to study greenhouse gas exchange processes as part of the European research project GreenFeedBack. The team sailed from Narsarsuaq, a small village in Southern Greenland, down to the Tunulliarfik Fjord. Detailed measurements were executed along the fjord axis onto the shelf, before the team sailed back to Zeebrugge, RV Belgica's home port. This final leg closed the onboard measurement program which started on June 6th and ran continuously while RV Belgica sailed on its first Arctic expeditions, executing science campaigns in Iceland and Greenland. The day that the team arrived in Narsarsuaq on August 3rd , a surprise was waiting on the port side: a beautiful iceberg!

Photo. RV Belgica at Narsarsuaq Port (Greenland). Photo credit: Bruno Delille.

What is GreenFeedBack?

GreenFeedBack (for greenhouse gas fluxes and feedbacks in the Earth system) is a European project focusing on the Arctic region, with the aim of improving our understanding of greenhouse gas exchanges in the terrestrial-freshwater-ocean ecosystem, as well as the impact of human activities.

Long-term changes have already begun in the Arctic (disappearance of sea ice, acidification of the oceans) as a result of climate change. The ocean/greenhouse gas component of the GreenFeedBack project aims to improve our understanding of the carbon cycle in Greenland's coastal zones and to describe the exchange processes between the coastal zones, the shelf and the open ocean. The aim is to improve climate models capable of predicting the future sink of marine carbon dioxide (CO2) in the Arctic. But it will also monitor changes in other greenhouse gases such as methane (CH4) and nitrous oxide (N2O), two gases with stronger effects than CO2, as well as changes in pH levels in order to track the acidification of these waters.

Who is the scientific team?

The team on board the RV Belgica was composed of five scientists from the Flanders Marine Institute (VLIZ) and the University of Liège (ULiège). The mission would not have been possible without the invaluable contribution of Hannelore Theetaert (VLIZ) and Wieter Boone (VLIZ), who helped set up the equipment and coordinated the campaign. The operational team and crew of RV Belgica also provided great support.

Photo. Bruno Delille (ULiège), Thanos Gkritzalis (VLIZ), Silke Verbrugge (VLIZ), Leandro Ponsioni (VLIZ) and Coraline Leseurre (VLIZ - APECS BE). Photo credit: Coraline Leseurre

What did they do onboard?

Our job onboard was to send a rosette into the sea. This ‘carousel’ was equipped with a CTD sensor (which continuously measures temperature, conductivity (salinity) and depth) and 24 10-litre Niskin bottles, which enabled us to collect water at different depths below the surface. At each sampling location, the rosette was sent down to the bottom and bottles were then closed on the way up. Once back on board, water samples were taken to perform various chemical analyses in order to quantify several greenhouse gases (CO2, CH4, N2O) as well as parameters of the carbonate system (pH, dissolved inorganic carbon and alkalinity) and organic matter dissolved in the water. Some samples had to be treated to interrupt any biological activity, so that the properties of interest could be well preserved until their analysis back on land. The data from the CTD sensors allowed us to observe the physical properties of the water and understand how the water circulates and moves along the fjord, as well as between the coast and the open ocean.

Photo. Lowering the rosette + CTD in Tunulliarfik Fjord (Greenland). Photo credit: Coraline Leseurre

The second part of our work consisted in using the vessel's capacity to pump surface seawater in the lab as it sailed. With the use of dedicated systems, we could then measure concentrations of greenhouse gases like CO2 and CH4 along the ship’s track. Finally, in order to validate these continuous measurements, we took discrete surface samples every 4 hours.

How is life on board?

The new RV Belgica, operational since late 2021, is a very comfortable research vessel. Modern cabins allow the scientists to get the rest needed to work long hours, and movie nights were held in the lounge provided for them. Delicious meals were prepared by the two cooks, and we had plenty of snacks available. Fortunately, the gym onboard helped us keep fit!

The working environment was fabulous. We were surrounded by rugged mountains, mostly untouched by humans, and translucent blue water covered on its surface by hundreds of icebergs. What was most impressive was the immense size of some of them. We were lucky to see one of these large icebergs break in front of us, and we even recorded it! ⬇️⬇️⬇️

Photo. Tunulliarfik Fjord and its icebergs (Greenland). Photo credit: Coraline Leseurre

Want to read more about the campaign and to feel even more immersed in this adventure? Have a look at the Polar Steps recount of the trip (loads more photos to enjoy)!

Written by Coraline Leseurre

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