Untangling the effects of climate change on ice shelf melting in the Amundsen Sea, Antarctica

Dr Kaitlin Naughten, Prof Paul Holland, Prof Alberto Naveira-Garabato
Rationale: 

Collapse of the West Antarctic Ice Sheet (WAIS) has the potential to cause over 3 metres of sea level rise, which would devastate coastal cities worldwide. The most immediate threat to the ice sheet is ocean warming in the Amundsen Sea. However, the processes which cause this warming are complex and poorly understood.

Over the last century, changes in the winds over the Amundsen Sea have likely driven ocean warming [1], by pumping warm water from the deep ocean onto the continental shelf. These wind changes are partially caused by human-induced climate change, and are expected to continue in the future [2]. However, over the next century, we also expect to see large increases in air temperature over the Amundsen Sea. It is not known how a warmer atmosphere will affect the ocean circulation in this region.

Which matters more to the Amundsen Sea: winds, or atmospheric warming? To what extent do these two climatic changes work in isolation, and how do they interact? Will atmospheric warming eventually take over from the winds as the dominant mechanism driving ocean warming in the Amundsen Sea? This project will use models to answer these fundamental questions about the future of the WAIS.

 

Methodology: 

This project will use the MITgcm (Massachusetts Institute of Technology general circulation model), which simulates ocean circulation, sea ice, and ice shelf melting. A high-resolution Amundsen Sea configuration of MITgcm is already used at BAS. The first task will be to reduce the model resolution so it is computationally cheaper to run. The model will be verified using existing observations, to ensure it simulates present-day conditions as accurately as possible.

MITgcm will then be used to run many simulations of the next century. First, it will be forced with atmospheric output from global climate models in CMIP6 (Coupled Model Intercomparison Project phase 6). Analysis of the results will determine the changes we can expect in Amundsen Sea ocean conditions as climate change continues. Then, the effects of winds and atmospheric warming will be separated, by constructing idealised forcing fields. MITgcm will be forced with (1) wind trends in isolation, (2) atmospheric temperature trends in isolation, and (3) both together in varying proportions.

These simulations will reveal which atmospheric variables matter the most for ocean warming and ice shelf melting, and on what timescales. The results will directly inform our understanding of future climate change and projections of sea level rise.

Location: 
BAS Cambridge
Training: 

The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at the British Antarctic Survey, Cambridge. Specific training will include:

  • Programming skills, primarily using Python, a language in high demand in academia and industry
  • Running and analysing MITgcm, one of the most widely-used models in ocean and climate research
  • Utilising parallel computing techniques on the UK national supercomputer, ARCHER2
  • Collaboration with the world-leading BAS Polar Oceans team
  • University of Southampton courses on Physical Oceanography, Climate Dynamics, and other relevant topics
  • Opportunities to attend conferences and workshops, in the UK and internationally
  • Opportunities to participate in Antarctic fieldwork as part of a potential research cruise to the Southern Ocean
Eligibility & Funding Details: 

Please see https://inspire-dtp.ac.uk/how-apply for details.

Background Reading: 

[1] Naughten, K., et al. “Simulated twentieth-century ocean warming in the Amundsen Sea, West Antarctica”. Geophysical Research Letters (2021): in review.

[2] Holland, P., et al. “West Antarctic ice loss influenced by internal climate variability and anthropogenic forcing”. Nature Geoscience 12 (2019): 718-724.