Examining climatic variability through time could be the key to projecting how the earth’s climate will change in the future, especially in response to global warming. Analysis of Antarctic ice cores is a critical tool to reconstruct past climatic adaptation and events through time. However, ice core analysis is limited by minimal available material and very low available biomass. Here, we use novel metagenomic sequencing approaches, coupled with strict ancient DNA methodologies, to obtained bacterial, archaeal, and fungal DNA from diverse Antarctic samples, including marine sediments, ancient calcite deposits, and large blue ice samples. Results from each location reveal unique biological patterns that change through space and time. By using detailed geochemical, morphological, and geospatial data, we are able to interpret the presence of specific microbial species trapped in ancient Antarctic samples to help inform large-scale climate models. For example, ancient metagenomic analysis revealed thermophillic microorganisms preserved within ancient calcite deposits in Western Antarctic. Alongside geochemical and morphological evidence, this finding supports a new hypothesis that hydrothermal activity and volcanism contributed to glacial melt over 20,000 years ago, which had the potential to impact global cycling patterns. Detailed examinations of bacterial community structure and species introductions can provide critical supporting evidence to understand past climate change in greater detail.