Australia: The Land Where Time Began

A biography of the Australian continent 

Greenland Meltwater Emerging Impact on the Formation of Deepwater in the North Atlantic

Since the 1990s, there has been increasing mass loss by the Greenland ice sheet (Chen, Wilson & Tapley, 2006; Sasgen et al., 2012). In the changing freshwater budget of the subarctic Atlantic the increased freshwater flux resulting from surface melting and discharge from outlet glaciers is assuming a role that is becoming increasingly important (Bamber et al., 2012). Böning et al. suggest that suppression of deep water convection in the Labrador Sea, which has potential ramifications for the Atlantic meridional overturning circulation, could result from sustained and increasing freshwater fluxes from Greenland to the surface of the ocean (Stouffer et al., 2006; Swingedouw et al., 2013; Rhamstorf et al., 2015). In this paper Böning et al. assess the impact of increases of the flux of freshwater, which they reconstructed with full resolution (Bamber et al., 2012), by the use of a global ocean circulation model with a grid spacing that was fine enough to capture the small-scale eddying transport processes in the subpolar North Atlantic. It has been found by these simulations that the invasion of fresh water from the West Greenland shelf has initiated a trend of gradual freshening at the surface of the Labrador Sea. The accumulation of meltwater may become large enough to dampen progressively the deep winter convection in the coming years, though the freshening is still smaller than the variability that is associated with the episodic ‘great salinity anomalies. Böning et al. conclude there has not yet been a significant impact by the freshwater anomaly on the Atlantic meridional overturning circulation.

Sources & Further reading

1. Böning, C. W., E. Behrens, A. Biastoch, K. Getzlaff and J. L. Bamber (2016). "Emerging impact of Greenland meltwater on deepwater formation in the North Atlantic Ocean." Nature Geosci 9(7): 523-527.