Bio-albedo : what is the extent of melting of the Greenland Ice Sheet caused by microorganisms ?

Séminaire de Alex ANESIO : mardi 14 mars 2017 à 10h, salle Lliboutry

Texte en français
Abstract : It is now recognised that large expanses of ice in the polar regions are inhabited by active microbial communities forming one of the biomes of Earth. Microbes on ice are diverse, play an important role in the cycling of nutrients and can also modify the physical environment they live. For instance, microbial processes at the surface of glaciers and ice sheets can lead to the accumulation of labile dissolved and particulate organic carbon and this in turn have consequences to the delivery of nutrients to adjacent ecosystems. Furthermore, the accumulation of cells often seen at the surface of the ice clearly results in ‘biological darkening’ of glacier surfaces. Such darkening increases the amount of incident shortwave radiation available for ice ablation, and could be a contributing element to glacier thinning and wastage.

“Fifty shades” of colour on ice surfaces :
a) white snow at the beginning of the melt season ; b) and c) green snow with its dominant main primary producer (Chlamydomonadales) collected from a Svalbard glacier ; d) and e) red snow with its dominant main primary producer (Chlamydomonadales) collected from a Svalbard glacier, f) and g) “dirty” ice with one of its dominant main primary producer (a Zygnematales) ; h) and i) an example of a cryoconite hole in the GrIS and one of its main primary producers (Phormidesmis priestleyi).

M. Alex Anesio is Professor of Biogeochemistry in the Bristol Glaciology Centre at the University of Bristol. He is the Director of the Bristol Glaciology Centre.

Séminaire animé par : Aurélien Domergue.