Investigating the influence of sea ice on Antarctic outlet glacier dynamics

The Antarctic Ice Sheet's contribution to global mean sea level rise has accelerated over recent decades. This is dominated by the dynamic imbalance of several major outlet glaciers in West Antarctica, driven by warm ocean currents melting the underside of their floating portions, causing ice marginal thinning, grounding line retreat and increased ice discharge. Similar processes have also been invoked to explain mass loss in Wilkes Land, East Antarctica.

Basal melting beneath ice shelves has the potential to reduce their buttressing effect and increase ice discharge from inland. However, recent work has also shown that buttressing forces can be provided by sea-ice and/or a mixture of calved icebergs bound together with sea-ice (known as mélange). This work has mostly been focussed on outlet glaciers in Greenland, where the presence/absence of sea-ice and mélange have been shown to influence the timing and sequence of calving events, seasonal changes in ice velocity, and longer-term patterns of glacier advance/retreat.

Although likely to be an important control on glacier dynamics, much less work has investigated the buttressing effect of sea-ice/mélange around Antarctica. Here, sea-ice occurs in much larger concentrations than Greenland, and preliminary work suggests that multi-year land-fast sea ice is an important control on ice velocity, major calving events, and the disaggregation/disintegration of floating ice tongues/shelves. There are also important feedbacks between sea ice and ocean stratification/temperatures, whereby reduced sea ice concentrations can lead to increased intrusions of mCDW. Furthermore, it is crucial to examine how the recent and dramatic decline in Antarctic sea ice might impact on glacier dynamics.

The overall aim of this Ph.D. project is to use remote sensing observations to explore the sensitivity of Antarctic outlet glaciers to variations in sea ice conditions.