Session 2B: Inaugural Lectures by Fellows/Associates

Biogeochemical Processes On Glacier And ICE Sheet Surfaces

While many people think of Earth’s glaciers and ice sheets as lifeless places, there is in fact abundant microbial activity with surprisingly huge impacts. Cyanobacteria and algae that live on the ice capture atmospheric CO2 and convert it into organic matter. Other microbes break down this organic matter, and that transported from further afield, such as soot from industrial activity and forest fires, releasing CO2 back into the atmosphere. Microbes modify and influence the nature of this organic pool, a portion of which is exported to coastal aquatic ecosystems through melt-water runoff. Large scale release of this organic carbon to the ocean due to accelerated ice loss from glaciers and ice sheets could have huge impacts on coastal food webs. Also, pigmented microbes together with light absorbing organics and mineral dust on the ice surface massively reduce the albedo of the surface (amount of solar energy reflected from the ice surface). This leads to increased absorption of solar radiation, resulting in faster melting of the ice – the single largest contributor to global sea level rise. Thus, microbial activity on ice influence not just greenhouse gas content and coastal food webs, but also melt rates and hence global climate and sea level rise.