Cryosphere microbial communities as a reservoir of hidden risks to human and ecosystem’s health

Cold environments harbour a variety of psychrophilic microbes adapted to survive in a range of habitats, such as sea-ice, permafrost, rivers, surface and subglacial lakes, and lake brines. In polar environments, which are partic- ularly sensitive to climate change, increasing temperatures and freezing-thawing phenomena of frozen substrates can lead to the release of cold-adapted microorganisms and also of non-psychrophilic species that have been trapped and preserved in ice for thousands to millions of years. Some of the dormant microorganisms can be re- activated, potentially threatening the eco-environment and human health. This review aims to summarize the current knowledge on potential pathogenic and biosecurity risks associated with both psychrophilic and non- psychrophilic microorganisms released following permafrost and ice melting, addressing some case studies re- garding the outbreak of infectious diseases. The potential impacts on public health underline the need for new strategies to prevent and manage new diseases caused by the release of ancient pathogens.