The main goal of this research project is to elucidate the fate of organic carbon stored in permafrost in the current context of climate change, looking at microbial-driven carbon degradation in active layer samples from the Lena Delta, Siberia and Herschel Island, Canadian Western Arctic. This is being accomplished by analyzing the abundance, dynamics and function of microbial communities involved in consuming this organic carbon, especially with respect to methane cycling. Microorganisms involved in methane cycling are of particular relevance in these frozen environments, as rising permafrost temperatures eventually lead to an increased degradation of previously conserved organic substrate. This in turn leads to an increased methanogenic activity, creating a potentially dangerous positive feedback-loop for climate change. The point of focus of this research is the biodiversity and function of microorganisms thriving in such difficult conditions, and their reaction to warming temperatures and a rapidly changing environment.Undergoing research activities include: T-RFLP analysis of methanogenic and methanotrophic communities in various active layer profiles from Herschel Island, incubation experiments under controlled variables to relate the methane production rate from active layer samples to rising temperatures, soil characteristics including soil moisture, C/N ratio, grain size, pH and trace elements. The results obtained will be scrutinized to answer the following questions: 1) Will the structure of microbial communities, particularly methanogenic and methanotrophic populations, be affected by rising permafrost temperatures? 2) Are these communities flexible enough to compensate the changes occurring in their environment with regard to carbon mineralization and their function in polar ecosystems? 3) How much of the carbon stored in permafrost is actually available for mineralization?