Polar and alpine microbiology in a changing world

High altitude and high latitude regions on Earth are experiencing rapid changes in climate. Ecological impacts resulting from these changes are now being observed at all ecosystem levels and larger deviations and more significant impacts are anticipated in the future. Satellite data show dramatic reductions in the extent and thickness of sea ice at both poles, and rising temperatures are causing alpine glaciers worldwide to shrink in area and volume. By virtue of their relatively rapid growth rates and metabolic diversity, we can expect microorganisms to be the first responders to fluctuating climatic conditions. Because microorganisms are keystone players in elemental transformations, variations in their abundance and diversity will initiate a cascade of impacts throughout entire ecosystems. Clearly, knowledge of the distribution, biodiversity and functional roles of microorganisms inhabiting polar and alpine environments is essential to our understanding of ecosystem processes in a changing climate.The continued warming and diminishing extent of the polar and alpine cryosphere will be a major driver of the microbially mediated processes occurring in these environments. We can expect to see changes in biodiversity, ecosystem and organismal stoichiometry, amplification of certain trophic levels, and a change in genomic connectivity among ecosystem components as the result of a warming cryosphere. Eventually, the climate-driven changes occurring in polar and alpine systems will reach critical thresholds or tipping points, if they have not …