This work package deals with the cryosphere and its links to the ocean and atmosphere. The focus is to examine the role of sea ice, glaciers and permafrost on physical, chemical and biological conditions in the Arctic. This involves the understanding of the effect of reduced sea ice conditions on the magnitude and regulation of sea ice algal communities, biogeochemistry, ocean acidification, brine, gas and chemical conditions in the sea ice and upper ocean, the ocean-ice-atmosphere boundary layer. This work package also deals with glacier-ocean interactions to understand the role of the ocean in melting the Greenland ice sheet (GIS), and how GIS meltwater influence coastal species and ecosystems, and its role for upwelling of nutrient rich deeper waters in the coastal domain. Effect of microbes on the stability of the GIS and cloud formation is also included. Finally the work package deals with permafrost and the potential for coastal erosion, release of greenhouse gases during warmer conditions. The feedback between Arctic and the rest of the World is also an important part of this work package e.g. sea level rise, fisheries, marine transport, ice hazards.