Expedition to study greenhouse gases in fjords
Carbon dioxide has long been in focus as a greenhouse gas. But recently, attention has also turned to methane and nitrous oxide. Researchers from the University of Gothenburg are now outside Bergen, Norway, on the research vessel Skagerak to investigate methane and nitrous oxide emissions from fjords.
Since the climate is affected by both natural greenhouse gases and those formed by human activity, more knowledge is needed about all sources of greenhouse gas emissions in order to estimate the future climate. The researchers are interested in finding out how much fjords contribute to greenhouse gas emissions, as they have been studied much less than lakes, estuaries, and the open sea.
“We want to find out how much carbon dioxide, methane, and nitrous oxide there are in the fjords to confirm existing budgets and estimate emissions. Other researchers on board will work on benthic foraminifera, on contaminants, and on carbon storage,” says Stefano Bonaglia, researcher at the Department of Marine Sciences, University of Gothenburg.
Three fjords north of Bergen
The researchers will investigate three fjords north of Bergen: the Fens, Mas and Haugsvaer fjords, where they will make geochemical measurements in the water column and in the sediment using a CTD, a rosette sampler, and various core samplers to collect sediment from the ocean floor.
“These three fjords have oxic zones, hypoxic zones, and anoxic zones, which makes them interesting from the chemical point of view. In addition, there is long-term data, so we can compare our measurements with previous years,” says Stefano Bonaglia.
Surprisingly large amount of methane emissions
In his previous research, Stefano Bonaglia has discovered that fjords are responsible for a surprisingly large amount of methane emissions to the atmosphere – emissions of this climate-warming gas are as large as from fjords as all the deep-sea areas in the world combined.
This is because fjords have a very specific design that has a major impact on greenhouse gas emissions. They are relatively sheltered from ocean currents and storms, creating oxygen-free bottoms in the fairly stagnant water.
Fjords also have shallower water than the deep sea, which means that the gases do not have enough time to break down completely before they reach the surface. Many rivers also flow into the fjords, carrying material from neighbouring lands such as farms, and the fjords therefore suffer from eutrophication.
Close knowledge gaps on emissions
“This type of research is important, as we live in a time when there is a great need for accurate science-based decisions regarding the management of greenhouse gases and eutrophication. We hope that our results will contribute to fill current gaps in understanding coastal greenhouse gases and lead to new, strong science-based arguments for how to take care of our beautiful fjords.”
What are you hoping to find?
“It would be nice to find trends in methane and nitrous oxide inventories, because their concentrations are nearly unknown in fjords . It would also be interesting to see how much carbon these fjords, which are relatively pristine, can sequester under current conditions, so that we can reinforce our current estimates of global carbon storage and greenhouse gas emissions from fjords,” says Stefano Bonaglia.
Writer: Annika Wall
You can see R/V Skagerak's position on Marine Traffic. The researchers are outside Bergen between 5 and 7 August 2024.
