Iceberg meltwater fluxes dominate the freshwater budget in Greenland's iceberg‐congested glacial fjords

TLDR

Freshwater fluxes from the Greenland ice sheet have increased over the last two decades due to rises in both liquid (surface and submarine meltwater) and solid ice (iceberg) fluxes. Here we use repeat ~0.5 m‑resolution satellite images from two major fjords to provide the first observation‑based estimates of the meltwater flux from the dense matrix of floating ice called mélange. We find that the ice mélange meltwater flux, driven by its expansive submerged area (>100 km²) and rapid melt rate (~0.1–0.8 m d⁻¹), can exceed that from glacier surface and submarine melting, indicating that iceberg melt within fjords must be considered in studies of glacial fjord circulation and Greenland melt impacts on the ocean.

Abstract

Abstract Freshwater fluxes from the Greenland ice sheet have increased over the last two decades due to increases in liquid (i.e., surface and submarine meltwater) and solid ice (i.e., iceberg) fluxes. To predict potential ice sheet‐ocean‐climate feedbacks, we must know the partitioning of freshwater fluxes from Greenland, including the conversion of icebergs to liquid (i.e., meltwater) fluxes within glacial fjords. Here we use repeat ~0.5 m‐resolution satellite images from two major fjords to provide the first observation‐based estimates of the meltwater flux from the dense matrix of floating ice called mélange. We find that because of its expansive submerged area (>100 km 2 ) and rapid melt rate (~0.1–0.8 m d −1 ), the ice mélange meltwater flux can exceed that from glacier surface and submarine melting. Our findings suggest that iceberg melt within the fjords must be taken into account in studies of glacial fjord circulation and the impact of Greenland melt on the ocean.