Climate modeling and IPCC projections argue that the global climate will warm significantly during the next century but that it will change dramatically in the Arctic. This is one motivation at the Alfred Wegener Institute for Polar and Marine Research to study this area in detail. Not only by accident, Arctic land masses are almost completely underlain by permafrost. Permafrost simply spoken is all ground material (rocks and earth) that remains frozen for at least two consecutive years. Approximately 25% of the northern hemisphere's land surface is underlain by frozen ground. Permafrost is formed when the ground is exposed to cold air over a long period of time.What kind of research are permafrost scientists doing and why? One big question is: How did the climate develop in the past? And how did landscape, vegetation, and animals respond to climate change? To answer this question is crucial to evaluate how the environment will respond to nowadays and future climate change. From meteorological observations data is limited to the last 150 years. But we need to look beyond to model the climate of the future and its impact. Permafrost is an excellent climate archive since everything buried and frozen remains intact and does not degrade for a long time.We use frozen sediments and unfrozen lake sediments in permafrost landscapes to reconstruct how landscapes evolved. Within these sediments the physical, chemical and biological properties help us to reconstruct past environmental parameters.Moreover, we look for gas and energy fluxes in the Arctic realm. The addressed question is: What happens over time with ground temperatures, carbon dioxide, and methane when weather and climate changes? Permafrost is the second largest storage for carbon next to the oceans. And what happens with this carbon when permafrost thaws? Is it released as greenhouse gases? What role do bacteria and archaeae play to degrade the carbon? Do they produce CO2 or CH4? What happens to microorganisms when permafrost is warming or cooling, when its getting wetter or drier?Humans, especially indigenous peoples are directly affected by a warming Arctic and warming permafrost. Coastal erosion is enhanced when ice rich coasts become unstable due to melting ground ice. Infrastructure built on the shore is threatened and sediment is washed into the ocean. This process is accompanied by the release of carbon, nitrogen, sulphur etc., and all kinds of contaminants. These elements are crucial for the arctic food web where indigenous peoples are at its end.