Distinct Ocean Responses to Greenland's Liquid Runoff and Iceberg Melt

Abstract

The annual mass loss (hereafter referred as discharge) from the Greenland Ice Sheet (GrIS) is currently estimated to be around 1,100 Gt/yr, half of which is attributed to liquid runoff and the other half to solid discharge (Bamber et al., 2012(Bamber et al., , 2018van den Broeke et al., 2009). While liquid runoff includes surface runoff and subglacial discharge, solid discharge is a product of the ice velocity and the glacier flux gate, located around the glacier's grounding line (Figure 1a;Bamber et al., 2018). Although other frontal ablation processes (such as submarine melting) are also responsible for transforming Greenland's solid discharge into liquid freshwater delivered to the ocean, most of this solid discharge can be attributed to the formation of icebergs (i.e., calving). Between 10% and 50% of those icebergs melt in the fjord (Enderlin et al., 2016), and the remaining drifts into open ocean. Because Greenland is situated close to areas of dense water formation such as the Labrador Sea, it follows that its freshwater discharge could reduce surface water salinities and thus increase water column stability to the point where deep convection is reduced or halted, disturbing the Meridional Overturning Circulation (MOC). However, despite the fact that this discharge from Greenland has been increasing over the last 20 years (Bamber et al., 2018), such enhanced freshwater has not impacted the MOC yet (Böning et al., 2016) since most of it does not directly reach the convective region of the

Sea Ice‐Driven Iceberg Drift in Baffin Bay

“…As this region is characterized by a negative surface freshwater flux from other sources (likely due to the predominance of sea ice formation; see Figure 3 from Marsh et al., 2015), the additional iceberg melt could be relevant for local freshwater budgets. The sea ice locking mechanism, therefore, can play a role — even if small — in keeping the iceberg meltwater away from the interior of the Labrador (Marson et al., 2021) and Irminger Seas, where it could interfere with deep convection processes (e.g., Böning et al., 2016).…”

“…Those icebergs, largely calved from Greenland (Kochtitzky et al., 2022), usually travel through Baffin Bay before reaching the busy shipping lanes over the Grand Banks (offshore eastern Canada, Figure 1). As they calve and melt through their journey, icebergs also impact freshwater distribution in the subpolar North Atlantic (e.g., Martin & Adcroft, 2010), which may alter local‐to‐regional ocean dynamics (Marson et al., 2021; Yankovsky & Yashayaev, 2014) and marine productivity (Bigg et al., 2021; Hopwood et al., 2019). All of these roles justify a more thorough investigation of their behavior.…”

Simulated Signatures of Greenland Melting in the North Atlantic: A Model Comparison With Argo Floats, Satellite Observations, and Ocean Reanalysis

“…The solid ice discharge is treated the same way as the liquid components (runoff of tundra and runoff of Greenland ice sheet) and a slower melting of the solid ice component is not (yet) considered. Thus, the transport of icebergs is neglected as well as the direct thermodynamic impact of their melting through latent heat fluxes (Marson et al., 2021).…”

Arctic freshwater impact on the Atlantic Meridional Overturning Circulation: status and prospects

“…One example is anthropogenic loss of the Greenland Ice Sheet (GIS), which has not yet led to detectable SPNA freshening [61,62]. Nevertheless, uncertainty exists on the fate of GIS meltwater because it depends on circulation model resolution, and how the GIS discharge is parametrized [62][63][64]. These processes are not accurately represented in the ECCOv4r4 state estimate.…”