Arctic Tipping Points

Our experimental campaign in Nuuk lasts 3 weeks. We live and work at the Greenland Institute of Natural Resources that also participates in the ATP project. Being located next to the sea with access to well-equipped and fast boats run by experienced boat drivers, a well-functioning laboratory, and inspiring and helpful employees, the place is ideal for studying the coastal ecosystem. Next to the laboratory is an annex building with apartments and individual rooms with common facilities for guest scientists and students. This is where we live during our stay.

The overall aim of our campaign is to obtain information on the growth of subarctic kelp forests and eelgrass meadows and their response to a future warmer climate where more light will reach the seabottom as the sea-ice retracts. Our activities incorporate field studies of the growth of kelp and eelgrass here in the north for comparison with that further south, since the present situation further south may simulate the future situation here in the north. We also conduct experimental studies of how kelps and seagrasses respond to increased seawater temperature.

For the experimental studies we have rented a cooling container from Royal Arctic Line and transformed it into a laboratory where we can grow seagrasses and kelp at temperatures ranging from the present summer seawater temperatures to temperatures up to +9 ˚C which covers the full range of projected scenarios for surface (air) temperatures in the Arctic by the end of the 21th century. The surface temperature of the coastal water around Nuuk is about 6˚ C in August and we had expected to use the temperature range 6-15 ˚C for our experiments. However, in the fjords where we sampled the vegetation the water temperature was typically around 10 ˚C so we decided to use the range 10-19 ˚C instead.

1. Our Royal Arctic Laboratory in front of the Institute of Natural Resources, Nuuk. Photo Dorte Krause-Jensen

The container awaited us in front of the institute when we arrived. The first couple of days were spent equipping the container with shelves, aquaria, temperature control units, heating systems, lamps, pumps etc. that we had sent in advance – also by Royal Arctic Line. Now the aquaria are populated with eelgrass and 3 species of kelp which will grow there for almost two weeks before we examine their responses to the warming. We have selected small individuals for the experiment so that we can fit them in our aquaria. The largest ones in the field are far too big – the biggest we found are almost 6 meters long! The three kelp species we use in the experiments are among the most dominant algae here and the same species also grow further south so we expect they will grow faster at the higher temperature treatments –up to a certain limit.

The container from the inside. Photo Peter Bondo Christensen

Close-up of the kelps and seagrasses growing in the aquaria. Photo Peter Bondo Christensen

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