Abstract
Runoff from the Greenland Ice Sheet (GrIS) is thought to enhance marine productivity by adding bioessential iron and silicic acid to coastal waters. However, experimental data suggest nitrate is the main summertime growth-limiting resource in regions affected by meltwater around Greenland. While meltwater contains low nitrate concentrations, subglacial discharge plumes from marine-terminating glaciers entrain large quantities of nitrate from deep seawater. Here, we characterize the nitrate fluxes that arise from entrainment of seawater within these plumes using a subglacial discharge plume model. The upwelled flux from 12 marine-terminating glaciers is estimated to be >1000% of the total nitrate flux from GrIS discharge. This plume upwelling effect is highly sensitive to the glacier grounding line depth. For a majority of Greenland’s marine-terminating glaciers nitrate fluxes will diminish as they retreat. This decline occurs even if discharge volume increases, resulting in a negative impact on nitrate availability and thus summertime marine productivity.
Authors
Hopwood, M.J., Carroll, D., Browning, T.J., Meire, L., Mortensen, J., Krisch, S. and E. P. Achterberg
Year
2018
Journal
Nature Communications
Citation
Hopwood, M.J., Carroll, D., Browning, T.J. et al. Non-linear response of summertime marine productivity to increased meltwater discharge around Greenland. Nat Commun 9, 3256 (2018). https://doi.org/10.1038/s41467-018-05488-8
Link
IASC Related Activity
The Importance of Arctic Glaciers for the Arctic Marine Ecosystem