production of data set time series of variables that describe the state of the atmosphere, land, ocean and the cryosphere. Sea ice is listed as one of the 13 Essential Climate Variables and the aim of [...] group is to produce datasets of sea ice concentration sea ice thickness sea ice drift that include Arctic and Antarctic sea ice and the respective uncertainties. The data sets both parameters will consist [...] thickness time series from data of the ERS-1, ERS-2, EnviSat and CryoSat-2 radar altimeter missions of Arctic and Antarctic sea ice. The production of a time-series of Antarctic sea-ice thickness is based on

Transdrift: Arctic Ice-Ocean-Interaction Understanding changes that appear at the major flux gates such as the Fram Strait , requires a closer look at the origin of the ice leaving the Arctic Ocean. It is assumed [...] significant regions of net ice production and export. Given the importance of the Laptev Sea for the Arctic Ocean sea ice budget, aim of the Russian-German Research Cooperation “Laptev Sea System”, is to investigate

sensitivity experiments addressing questions such a What would happen to the global climate system if Arctic sea ice vanished? Climate models are also used in the Climate Dynamics section to carry out predictions [...] Traditionally, theoretical work in the Climate Dynamics section focusses on the behaviour of the ocean.

Network SPICES: Detection and forecasts of ice covers Changing Arctic Ocean ESA: Climate Change Initiative MOSAiC IceBird Transdrift: Arctic Ice-Ocean-Interaction

used for the interpretation of glacial processes. Ice sheet scours on the Lomonossov Ridge in the Arctic Ocean Madiba Sea Mount, south of South Africa, discovered 2013 with RV Polarstern Current-induced seabed [...] data is used as basic key parameter for many marine processes. They are necessary to understand ocean currents, mass transports (e.g. landslides) and tectonic processes. Also for habitat studies these

role in Arctic Ocean geophysical research for many years and in various projects. Projects Formation of new seafloor at the Arctic Mid-Ocean Ridge International Bathymetric Chart of the Arctic Ocean (Photo: [...] Formation of the Arctic Basin The Arctic Ocean is of particular geological interest. It hosts a wealth of different geological provinces ranging from deep ocean basins over prominent ridges to vast shallow [...] perennial sea ice-cover, information on the geological history of the Arctic Ocean is still sparse. As the sea-ice recedes, the Arctic Ocean will see an explosion of research activities. With RV Polarstern

better understand and quantify the role of clouds in the lower Arctic atmosphere. A special focus is on the amplified climate change in the Arctic. To that aim measurements during ACLOUD and AFLUX were/are [...] Airborne Observations In, Below and Above Arctic Clouds Map of the areas for aircraft operation illustration the coordination activities at Polarstern and Ny Alesund (Photo: Alfred-Wegener-Institut) ACLOUD [...] research institutes (listed below) embedded in the Transregional Collaborative Research Centre TR 172: ArctiC Amplification: Climate Relevant Atmospheric and SurfaCe Processes, and Feedback Mechanisms (AC)³

Earth System Models We simulate Arctic sea ice for the past, current and possible future climates, with regional sea ice-ocean and Earth System Models. Regional ocean-sea ice models have the advantage [...] al., 2014 ). We test those parameterizations in regional sea ice ocean models such as NAOSIM ( Köberle and Gerdes, 2003 ) and an Arctic model set-up of the MITgcm ( Castro-Morales et al., 2014 ). After [...] usually much coarser spatially resolved but have the advantage of simulating the atmosphere model, the ocean and the sea-ice simultaneously. Earth System Models (ESMs) additionally include vegetation and chemistry

Tallinna Tehnikaülikool (Estonia) Gronlands Naturinstitut (Greenland) Arctic Monitoring and Assessment Programme Secretariat World Ocean Council EU-PolarNet Participants (Photo: Alfred Wegener Institut)

Prediction A “weather forecast” for the Arctic No-one can say for sure whether the next few days will be snowy or sunny at the North Pole: the weather forecast for the Arctic is far less reliable than for other [...] researchers hypothesize that the warming of polar air masses and the retreat of ice cover in the Arctic Ocean are currently responsible for a change in global weather and climatic activity: while changes [...] more common. Climate change is impacting the Arctic In addition, rising temperatures and dwindling sea ice are affecting the indigenous peoples of the Arctic, who have always been able to rely on their