"Fifteen percent of the world’s soil carbon stock is currently kept frozen in permafrost soils from the arctic region.Recent climatic projections have indicated that this environment is particularly at risk due to global warming, with up to 90% of the near surface that could be thawed by 2100. Related revival in microbial activities could initiate the most dangerous amplifying feedback in the entire carbon cycle, boosting global warming as a result of a massive release in greenhouse gas. Permafrost also represent a potentially massive repository of viruses, genes and naked DNA fragments, that sometimes have been preserved in situ for up to hundreds of thousands years.While representing a fantastic potential for innovative biotechnological applications, this genetic reservoir could turn as a major threat to human health as once thawed, vast amounts of new antibiotic-resistant determinants might be made available for horizontal gene transfer, promoting the emergence of new resistant pathogens worldwide. The potential extent of greenhouse gas production and bacterial outbreaks will ultimately depend of the metabolic, cellular and molecular complexity present in permafrost.Here, we propose to characterize the permafrost microbial and viral communities, as well as the extent of the antibiotic resistome, using massively parallel next-generation sequencing. In addition, ancient DNA technologies will be used in order to track back permafrost response to previous episodes of global warming, which will serve as a proxy for the ongoing global warming.This project will reveal the true balance between sources and sinks of greenhouse gas in permafrost. Potential future escape routes to current therapeutic agents will be identified through the characterization of new allelic variants in major antibiotic resistance genes; hence, this project will improve our ability to predict and fight the future effects of global warming and related emergence of new infection types."