Detalle de: A 2-million-year-old microbial and viral communities from the Kap Kobenhavn Formation in North Greenland

Summary Environmental DNA (eDNA) from the 2-million-year-old Kap København Formation of northern Greenland has revealed an ecosystem of plants and animals with no contemporary analogue 1 . Here, we reconstruct the microbial (bacterial, archaeal, and viral) communities that thrived at the site during this time. By leveraging a novel analytical framework that integrates taxonomic profiling, DNA damage estimates, and functional reconstructions, we identify and distinguish pioneer microbial communities from later permafrost microbial assemblages. We show that at the time of sediment deposition, the terrestrial input at the Kap København site originated from a palustrine wetland, suggesting warmer, non-permafrost conditions. During this period, the detection of methanogenic archaea and signals of their carbon metabolism is consistent with Kap København and similar northern ecosystems contributing moderate methane emissions. Intriguingly, we discover a remarkable nucleotide sequence similarity—exceeding 98%—between pioneer methanogens and present-day analogues in thawing permafrost. This aligns with the concept of “time-traveling” microbes 2 surviving across geological time and waiting for conditions to turn favourable rather than evolving to adapt to changing conditions. Importantly, in contrast to the plant and animal communities of the Kap København, a striking similarity in microbial composition to that of a contemporary thawing Arctic suggests that microbial communities may serve as the first indication of broader climate-driven ecosystem disruptions.