Subglacial and Proglacial Ecosystem Responses to Climate Change

Abstract

Life beneath glaciers requires efficient adaptive strategies in order to thrive in these extreme habitats that are characterized by nutrient and energy limitation, low temperatures and reduced water availability. Together with the deep subsurface and the deep oceanic basins, subglacial (beneath glaciers) environments are among the last biosphere-exploration frontiers on Earth. At present we have only a vague idea about the types of organisms that live beneath ice sheets and glaciers as well as their characteristics (Willerslev et al., 1999, 2007). As a consequence we do not know what will happen to them as climate amelioration causes glaciers worldwide to recede and disappear. What we observe today in almost all glacierised regions of the World is that previous subglacial environments change into proglacial (in front of glaciers) environments, where the environmental conditions are very different. In this chapter we will provide an overview of our current knowledge on the subglacial and proglacial ecosystems, and highlight potential consequences of climate change on these habitats. The multidisciplinary study of subglacial and proglacial ecosystems, is only in its infancy and the literature is rapidly expanding. The reported results are not only relevant for our understanding of biological diversity and adaptability in general, but they also provide the foundation for hypotheses on how we imagine life survived during the periods where the Earth was totally ice-covered (the so-called Snowball Earth glaciations) and how life may survive on Earth in case of a global nuclear disaster (the so-called Nuclear Winter). In fact, the results may seed far-reaching theories on whether subglacial environments may host past or present extra-terrestrial (astrobiological) habitats on Mars, Jupiter’s moon Europa, Saturn’s moon Titan, and even on planets and moons beyond our solar system (Des Marais et al., 2008). In addition, cold-adapted organisms may also provide a valuable source for enzymes that may have biotechnological applications (Reddy et al., 2009). A prerequisite for life as we know it is liquid water required for biochemical processes, electrochemical gradients and transfer of chemical substances. The occurrence of water in subglacial environments is largely dependent on the subglacial thermal regime. Beneath cold-based glaciers, i.e. glaciers where the sole is frozen to the substratum, liquid water is a limited resource and may be primarily restricted to a few subglacial channels. However, it