With its consequences for the weather, sea level and ecosystems, global warming following the emissions of anthropogenic CO2 to the atmosphere is among the great societal challenges of our time. There is a strong need for knowledge to underpin long-term strategies for adaptation as well mitigation measures.
The project Subpolar North Atlantic Climate States (SNACS) deals with the ocean areas to the south and southwest of Iceland, the Irminger- and Labrador Seas. Observations obtained over the last couple of decades have allowed us to witness how these areas have undergone massive changes in response to atmospheric forcing associated with natural climate variability. Both deep-water formation and surface circulation have proven themselves sensitive to climate fluctuations, with ramifications for the amount of CO2 stored in the ocean and the properties of the Atlantic water that flows into the Norwegian Sea. These processes now provide us with a strong framework for understanding future ocean response to climate change and its consequences for potential feedback mechanisms such as heat transport and carbon uptake.
SNACS will take a multidisciplinary approach to understand and predict the subpolar North Atlantic. SNACS will conduct a number of field studies targeting the present behavior of the SPNA. This includes hydrographic cruises, and autonomous sampling from ships of opportunity and drifting boys. These data will be combined with data collected at past campaigns and used to unravel the processes that give rise to the variability we observe today.
SNACS will dig into the past behavior of the SPNA through using high-resolution sedimentary archives that provide information on the surface- as well as deep- ocean conditions. Among other things thin layers of volcanic ash will be used to determine the exact phasing of deep-surface changes and their relation to historical climate changes.
SNACS will look into the future by employing simulations from the set of models used for the upcoming 5th assessment report from the Intergovernmental Panel on Climate Change. Our observations from the present and from past times will be used to rank the model performance and the best models will be used for a quantitative assessment of SPNA behavior under global warming and how it may feed back on climate development.
The subpolar North Atlantic acts as a gatekeeper to the north; it controls the properties of the Atlantic Water that flows into the Nordic Seas. It is the crossroads to the south; deep waters formed in the north pass through this region on their way to the deep western boundary current. SNACS will obtain and use observed and simulated data from this important region, generating quantified assessments of future climate change under CO2 emission scenarios. This will form a basis for the required policy actions rooted in scientific facts
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