Sensitivity of East Antarctic outlet glaciers to recent and future climate change

Overview

Dynamic changes in marine-terminating outlet glaciers in Greenland and West Antarctica indicate that their contribution to sea level rise has accelerated in the last few decades (Shepherd et al., 2018). This is largely due to increased velocity, thinning and retreat, which has been linked to both atmospheric and oceanic warming. In contrast, the world’s largest ice sheet – the East Antarctic Ice Sheet (EAIS) – has generally been perceived as much less vulnerable. However, mass loss has been detected in some regions (e.g. Wilkes Land: Rignot et al., 2019), and recent work suggests that its marine-terminating outlet glaciers respond rapidly to external forcing at decadal time-scales (Miles et al., 2013; 2016; 2017; Greene et al., 207). Recent studies have also noted the widespread movement and ponding of surface meltwater on numerous East Antarctic ice shelves (Stokes et al., 2019), including some that exert a significant buttressing effect on inland ice flow and which may be vulnerable to collapse via meltwater-driven hydrofracturing. This suggests that the EAIS may be more vulnerable to future climate change than previously thought, and numerical modelling suggests that some regions grounded below sea level may be close to the threshold of instability (Mengel and Levermann, 2014; DeConto and Pollard, 2016).

Despite growing evidence for the potential vulnerability of the EAIS, and unlike in Greenland and West Antarctica, there are few detailed observations of many of its large marine-terminating outlet glaciers (Figure 1). As such, we know very little about what controls the behaviour of outlet glaciers in the EAIS. To address this issue, the overall aim of this project is to use remote sensing observations to explore the sensitivity of major East Antarctic outlet glaciers to oceanic and atmospheric forcing.

The primary research questions are:
• To what extent are EAIS outlet glaciers sensitive to atmospheric or oceanic forcing?
• How does outlet glacier response to forcing vary between different climatic or topographic settings in East Antarctica?
• How do specific glacier characteristics increase or decrease sensitivity to various forcings (e.g. the presence of ice tongues, ice shelves, bed topography)?

Click on an image to expand

Image Captions

Figure 1: Major outlet glaciers draining the East Antarctic Ice Sheet in Victoria Land.

Methodology

The project will focus on several large marine-terminating outlet glaciers in various climatic and topographic settings across the EAIS. Initially, a variety of remote sensing data (e.g. Landsat, Sentinel, ICESAT2) will be used to determine changes in frontal position, ice velocity and ice surface elevation over the last few decades (depending on data availability), with annual to sub-annual resolution available from the 2000s. Temporal trends will then be compared to possible atmospheric (air temperatures, precipitation) and oceanic forcing (temperatures at various depths, sea ice concentrations). These data will be obtained from readily available satellite and reanalysis products (e.g. NCEP/NCAR climate reanalysis data; Hadley Centre EN3 ocean temperature data; etc.), and, where available, meteorological and ship-based measurements. Evaluation and statistical analysis of these empirical datasets will be used to test hypotheses that seek to explain outlet glacier behaviour in the different climatic and topographic settings.

Optionally, depending on student interests and skills, there is scope to incorporate a numerical modelling element to further test hypothesised controls on outlet glacier behaviour and explore their future evolution. For example, modelling could apply oceanic and atmospheric forcing processes, such as surface melt, ocean melt, changes in ice shelf or sea-ice buttressing, and basal lubrication in order to test the sensitivity of key glaciers.

Project Timeline

Year 1

Training in Remote Sensing and GIS; review of relevant literature and datasets; collection and analysis of remote sensing datasets of major East Antarctic outlet glaciers

Year 2

Collection and analysis of atmospheric and oceanic datasets; set-up optional numerical modelling and perform validation against observations

Year 3

Analysis of specific glaciers identified in initial two years. Conduct optional sensitivity experiments of past and future behaviour using numerical modelling. Prepare research papers; conference attendance

Year 3.5

Further modelling and submission of research papers and thesis; conference attendance

Training
& Skills

The student will receive both generic and bespoke training in Remote Sensing and GIS, including software such as ERDAS Imagine, ArcGIS and NEST Array. Numerical modelling skills will be provided via ‘hands-on’ training from the supervisory team, and specific training in Matlab and statistical software (e.g. Stata), supplemented with an internationally-recognised summer school in Karthaus and numerical modelling training workshops. Broader transferable skills (e.g. communicating science, thesis writing, writing for publication, presentation skills) will be developed through various training events at Durham University offered by IAPETUS. We anticipate this project will be completed as a series of publications/papers led by the student.

References & further reading

DeConto, R.M. & Pollard, D. (2016) Contribution of Antarctica to past and future sea-level rise. Nature 531, 591-597.
Greene, C.A. et al. (2017) Wind causes Totten Ice Shelf melt and acceleration. Science Advances, 3, e1701681.
Mengel, M. & Levermann, A. (2014) Ice plug prevents irreversible discharge from East Antarctica. Nature Climate Change, 4, 451-455.
Miles et al. (2013) Rapid, climate-driven changes in outlet glaciers on the Pacific coast of East Antarctica. Nature, 500, 563-566.
Miles, A.W.J. et al (2016) Pan-ice sheet glacier terminus change in East Antarctica reveals sensitivity of Wilkes Land to sea-ice changes. Science Advances, 2 (5), e1501350.
Miles, A.W.J. et al. (2017) Simultaneous disintegration of outlet glaciers in Porpoise Bay (Wilkes Land), East Antarctica, driven by sea-ice break-up. The Cryosphere, 11, 427-442.
Rignot et al. (2019) Four decades of Antarctic Ice Sheet mass balance from 1979-2017. Proceedings of the National Academy of Sciences, 116 (4), 1095-1103.
Stokes, C.R. et al. (2019) Widespread distribution of supraglacial lakes around the margin of the East Antarctic Ice Sheet. Scientific Reports 9, 13823.
Shepherd, A. et al. (2018) Mass balance of the Antarctic Ice Sheet from 1992 to 2017. Nature 558, 219-222.

Further Information

Professor Chris R. Stokes
Durham University
E-mail: c.r.stokes@durham.ac.uk
Tel. 0191 334 1955

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