The impact of climate change on Arctic blue carbon (BlueARC)

BlueArc provides new knowledge on the impact of climate change and other stressors like sea urchins on Arctic kelp forests, with a focus on how future Arctic conditions will alter kelp carbon sink potential. In the first year of the project BlueArc conducted SCUBA diving field sampling in Svalbard and coastal Norway to measure kelp forest structure, productivity and carbon export. We modelled this export in the Arctic, and globally, and found 56 million tonnes of seaweed carbon can reach deep ocean sinks annually. We collected deep cores in the Canadian High Arctic off the R.V. Amundsen that we will use to verify this kelp export for remote Arctic regions. During our dive trip in Svalbard, we observed extensive sea urchin overgrazing at historic kelp forest sites, suggesting grazing could intensify as temperatures warm. We also measured associated in fauna on Arctic kelp forests, and showed these are sites of elevated benthic biodiversity. Finally, we experimentally demonstrated reduced kelp carbon sequestration potential with warming seawater temperatures due to faster remineralization rates of kelp forests. We have published our project results in top ecology and nature journals and the project was featured on NRK. This work will be a significant step forward in our understanding of carbon cycling by Arctic coastal ecosystems.

Over 20% of the world’s kelp forests occur along Arctic coastlines, yet shifts in the structure and ecological function of these habitats as a result of climate change are poorly understood. Kelp forests are highly productive ecosystems and are expected to contribute significantly to global carbon cycling and CO2-mitigation through blue carbon sequestration. Warming and reduced sea ice cover are predicted to expand kelp forests in the Arctic, which, coupled with slow and incomplete decay in cold waters, represents a potential increase in kelp carbon sequestration capacity. Knowledge on the factors regulating kelp carbon production and fate is however currently scarce in these regions, but critical to assess the impact of climate change and other stressors on Arctic carbon cycling. BlueARC will conduct field work across Arctic biophysical gradients to understand the conditions regulating kelp biomass, production and detrital export. The project will also quantify the fate of kelp carbon by identifying environmental and biological processes that alter detrital transport to potential deep ocean sinks across the subarctic to Arctic transition, and use degradation experiments, oceanographic models and genetic tools to trace kelp-carbon buried on arctic shelves. BlueARC will bring together researchers Scandinavia, Russia, Canada, Denmark and Greenland to provide new data on spatial extent and carbon standing biomass of kelp ecosystems, and to test overarching hypotheses on climate-driven impacts on their potential as coastal carbon sinks. The study area integrates subarctic and Arctic regions in the north Atlantic: from Nunavut and Labrador in Canada, across western Greenland, to northern Norway and Svalbard, and finally to the White Sea in Russia. The resulting knowledge will by synthesized to predict how rapidly changing arctic conditions will alter kelp carbon sinks and by mapping carbon storage and sequestration potential across the Arctic now and in the future.