New paper shows Greenland ice surface albedo controlled by distributed biologically-active impurities

The Greenland Ice Sheet (GrIS) is the largest cryospheric contributor to global sea-level rise. The dominant energy source for snow and ice melt is direct solar shortwave radiation, the absorption and reflection of which is predominantly modulated by surface darkness (albedo). We have shown previously that algal growth is a crucial control of bare ice darkening on the GrIS.

A new study has been published in Nature Communications, led by Johnny Ryan from Aberystwyth University and co-authored by Marek, that brings another piece of the (bio)albedo mosaic. It demonstrates that distributed surface impurities — an admixture of dust, black carbon and pigmented algae — explain 73% of the observed spatial variability in albedo and are responsible for the so-called ‘dark zone’ in the southwest of the GrIS. It is likely that the ongoing emergence and dispersal of distributed impurities, amplified by enhanced ablation and biological activity, will drive future expansion of Greenland’s dark zone.

Dark zone on the Greenland ice sheet (photo: J. Ryan)

Ryan JC, Hubbard A, Stibal M, Irvine-Fynn TD, Cook J, Smith LC, Cameron K, Box J (2018) Dark zone of the Greenland Ice Sheet controlled by distributed biologically-active impurities. Nature Communications 9:1065 doi: 10.1038/s41467-018-03353-2