This cruise will be a bit of an adventure, in that it is the first time someone attempts to search for methane release through the seabed during winter times in the area.
Text and photo: Mauro Pau, postdoc CAGE
A group of 16 scientists and engineers from eight different countries and three different institutions embark on the icebreaker R/V Kronprins Haakon. Destination: the North-East Greenland continental margin in the dark and frigid polar night. This is an extremely appealing study area because
1) it has been scarcely studied due to difficulty of access;
2) it can reveal precious information on how ice sheets influence the global carbon cycle;
3) we want to investigate how much methane is currently being released through the seabed;
4) it is not even clear where the Greenland Ice Sheet margin was at its maximum extension.
This cruise will be a bit of an adventure, in that it is the first time someone attempts to search for methane release through the seabed during winter times in the area. We are planning to conduct multibeam echosounder, sub-bottom profiler and hydrographic surveys, in addition to acquire sediment cores and possibly deploy a heat-flow probe. Uncertainties on what we will find are large, but this is precisely what scientific research is about: to go in search of the unknown with no guarantee of finding what is expected or anything at all.
16th–17th November 2020
Due to some technical issues, we have to delay our departure. Many of us take therefore the opportunity to have a look around Longyearbyen, the main settlement of the Svalbard archipelago and our port of departure. Interestingly, we all make it back to the ship in one piece, despite the warning of a polar bear in search of someone to make dinner of. The extra time in port is also appreciated as it gives us the opportunity to set up the labs while the ship is not yet dancing on the waves. We finally leave around 7 PM on the 17th and move smoothly out of Isfjorden at the speed of ten knots.
18th November 2020
We reach the first survey station, just offshore Svalbard, around 2 AM. This means that some of us start their workday at that time. Traditional rhythms used on land do not apply at sea. At sea, all are based on the weather conditions, so work can happen at any time – provided that at least 10 hours of rest are observed for each 24-hour period. The first station is of interest to the ‘DNA team’ from NORCE (Norwegian Research Centre; more of their work later). Meanwhile, the wind picks up to the level of gale to strong gale (8 to 9 in the Beaufort scale). The wind comes from the north, i.e. perpendicularly to our course, and is accompanied by 6-7 metre high waves. The captain’s only option is to steer the ship diagonally across the wave crests, thus avoiding a dangerous and extremely uncomfortable rolling. Many get seasick, and it is only late in the evening that wind and waves allow us to head westward again.
19th November 2020
We wake up at the sound of the blocks of sea ice hitting the hull of the ship. In the beginning, they are only sparse blocks, but as the day progresses the sea becomes entirely covered by large chunks of ice. The view over the glaciated Arctic Ocean is stunning, as is the fact that the ship now remains rather stable. It is around lunchtime when we cross the Greenwich Meridian. Below us are over 2600 metres of water.
The ‘acoustic team’ from CAGE (more of them in a later entry) measures the sound velocity along the water column so as to calibrate the hull-mounted multibeam echosounder and sub-bottom profiler. We then start recording a transect with these instruments across the Greenlandic continental slope, knowing however that sea ice generates plenty of extra reflections, thereby disturbing the data. We proceed through the ice pack at a speed varying between 2 and 5 knots according to the thickness of the ice we encounter.