Permafrost in arctic and subarctic lowlands

In recent decades permafrost landscapes in the arctic and subarctic lowlands have experienced warming resulting in a clear rising trend of permafrost temperatures despite some inter-annual variability and occasional cooling or stabilization. A widespread general deepening of the active layer, on the other hand, has not been observed. Changes in the carbon cycle of permafrost ecosystems also remain inconclusive due to a limited number of studies and their usually much localized focus. During the Quaternary environmental history of the Arctic, the non-glaciated Siberian lowlands have repeatedly experienced times of permafrost formation and permafrost degradation. Thus, the climate-change related long-term processes of permafrost dynamics can be reconstructed using environmental indicators from permafrost archives. Additionally, the amount of fossil organic material stored in the permafrost documents the permafrost's relevance for the global carbon cycle. In order to determine the current state and extent of permafrost ecosystems with regard to their thermal, hydrological, geomorphological, and carbon gas emission characteristics, a comprehensive standardized monitoring network combining remote sensing, modelling, long-term observations, and detailed process studies is urgently needed. Only if the current state of permafrost is well known, changes can be detected and future trends and developments can be predicted. That prediction in turn requires a thorough understanding of the paleoenvironmental history of permafrost landscapes