PhD Studentship: The role of icebergs in heat, freshwater and nutrient exchanges in Greenland’s fjords

We have an exciting opportunity to support a 3.5 PhD project as part of the UKRI-funded “Fjords Exchange Heat, Freshwater and Nutrients between the Greenland Ice Sheet and the North Atlantic Ocean (FEISO)” project. The successful candidate will join a growing team investigating Greenland ice-ocean interactions.

Background

Mass loss from the Greenland Ice Sheet has accelerated rapidly, especially at marine-terminating glaciers, which flow into fjords. These fjords are a natural bottleneck between the ice sheet and the ocean, through which warm ocean water and fresh meltwater must transit. The fjords and nearby coastal waters also host productive fisheries that form the backbone of Greenland’s economy. Therefore, fjords are key to understanding Greenland ice-ocean interactions.

This PhD project will investigate how icebergs, which are abundant in Greenland’s fjords, affect the transfer of ocean heat to the ice sheet, the export of freshwater to the ocean and the productivity of Greenland’s fisheries. Icebergs act as mobile heat sinks and localised freshwater sources, which alter fjord circulation and have poorly-constrained impacts on marine-terminating glaciers. Furthermore, iceberg melting releases nutrients and drives localised upwelling, which draws nutrient-rich deep water into sunlit surface waters. This stimulates phytoplankton blooms, sustaining the rich marine ecosystems and local fisheries upon which Greenlandic communities rely. Modelling of icebergs in fjords is in its infancy, with some processes poorly represented or underexplored; therefore, coastal primary production, freshwater export, and up-fjord heat transport may be misrepresented in these models or poorly characterised in our conceptual understanding of these systems.

Objectives

This PhD project will use an ocean circulation model and remote sensing to quantify the impacts of iceberg deterioration on Ilulissat Kangerlua, an iceberg-congested fjord in west Greenland that hosts one of the world’s fastest glaciers and connects to highly productive fisheries. Potential objectives are:
1. Quantify iceberg-induced changes to glacier melt rates: simulate the feedbacks between iceberg melt and fjord circulation to quantify how icebergs have influenced oceanic heat delivery to marine-terminating glaciers over the past three decades.
2. Determine the fate of freshwater from iceberg melt: use tracer experiments to characterise the timing, distribution and modification of iceberg meltwater as it transits and eventually exits fjords.
3. Quantify nutrient upwelling dynamics: examine how changes in iceberg concentration, depth and distribution over the past three decades has affected the primary productivity of Ilulissat Kangerlua and nearby coastal waters.

The successful candidate will have the freedom and support to focus on one or multiple of these objectives, and adapt the research to their interests as the project progresses, within the scope of FEISO.

Novelty and timeliness

Over the past three decades, research into Greenland’s tidewater glaciers has focused on the glacier-ocean interface and the impact of glacial meltwater on fjords. It is only in recent years that icebergs have been recognised as an important component of the glacier-fjord system. Thus, their impacts remain insufficiently understood and may be misrepresented in projections of ice sheet, climate and sea level changes. Recent developments in numerical modelling and remote sensing capability, and increasing availability of in-situ observations, now allow for accurate measurements and simulations of iceberg production, drift, deterioration, and impacts on fjord dynamics. By bridging physical glaciology, oceanography, and marine biogeochemistry, this project will provide vital insights into the behaviour of the Greenland Ice Sheet and its coastal waters.