Energy for Life: From the Land of Fire and Ice to Europa, and Beyond

In the search for life elsewhere, the mantra is “follow the water”, but life as we know it not only needs water as a solvent for biochemistry, but energy to drive reactions.  On Earth under a Faint Young Sun, In the icy satellites of Jupiter and Saturn, and on extrasolar planets beyond the “habitable zones” of their host stars, thick ice crusts could prevent photosynthesis, and life may instead rely on disequilibrium chemistry maintained by volcanic activity.  Over the past 20 years we have investigated the chemistry and biology of subglacial volcanic lakes in Iceland as analogs to these potential habitats.  Our studies reveal novel microbial ecosystems that are remarkable in their metabolic and taxonomic simplicity.  Our findings have potential implications for any atmospheres on these bodies as well as searches for  biosignatures.  Lastly, I will relate how we better understand the hydrology of these systems by inadvertently triggering one of the largest floods on modern Earth.