NSFPLR-NERC: Geological history constraints on the magnitude of grounding line retreat in the Thwaites Glacier system

We propose to obtain geological evidence from the Thwaites-Pine Island glacier system that will show whether glaciers were less extensive than they are at present, and, if so, when. Our goals are to: (i) determine whether previous grounding-line retreat-advance cycles, as suggested by existing geological evidence, occurred in the late Holocene, and (ii) establish under what climate and sea-level boundary conditions they took place. Determining the conditions under which the Thwaites and Pine Island Glacier grounding lines have retreated and re-advanced in the past is critically relevant to determining whether or not present-day grounding-line retreat is irreversible.

We will utilize two approaches to achieve these goals. To obtain geological evidence for past grounding-line retreat episodes, we will apply cosmogenic-nuclide exposure-dating of subglacial bedrock. Using drill systems recently developed in the USA for subglacial bedrock recovery and proven in the 2016-17 Antarctic field season, we will obtain subglacial bedrock from sites where ice thickness is dynamically linked to grounding line position in the Thwaites system. The observation of significant cosmogenic-nuclide concentrations in these samples would provide direct, unambiguous evidence for past episodes of thinning linked to grounding line retreat as well as constraints on their timing and duration. To reconstruct Holocene relative sea level, we will map and date raised marine and shoreline deposits throughout Pine Island Bay.

The project will have broad societal impact via the following public engagement and outreach programmes in the US and UK:

1. Mobile, dynamic, physical sea-level visualization: It is common practice in coastal and riverine cities throughout the US, UK, and elsewhere to mark the height of significant historical floods on buildings, telephone poles, or other structures. This provides a sense that city residents have endured shared hardships, a powerful reminder of vulnerability to natural processes, and a spur to planning and preparedness against future flooding. Brent Goehring (Tulane University, USA) will start with this idea, migrate it from past to future sea-level rise scenarios, and realize it as a mobile, dynamic visualization tool that attracts and fixes public attention.

2. Outreach to UK schools: We will undertake a programme of public engagement, in particular outreach to schools, through the existing 'Think Geophysics' initiative run by Woodward at Northumbria University, which builds on the nuSTEM project led by Northumbria (currently funded at £1.2 million by the Higher Education Funding Council for England). nuSTEM targets gender imbalance in physics at UK universities by changing the way young people engage with science during their school years and path to university, and works with 40 partner schools, aiming to engage over 100,000 young people by 2025. 'Think Geophysics' will adapt the nuSTEM cradle-to-career blueprint to environmental geochemistry and geophysics, aiming to inspire young people, particularly women and underrepresented groups, into science careers through the following actions: Engage pupils at 20 partner schools through 'Think Geophysics' workshops that cover climate change in Antarctica including sea level rise, introduce key concepts in geochemistry and geophysics, and allow children to explore these themselves through hands-on activities. In conjunction with a local artist, bespoke workshops will be developed to help young people explore scientific concepts of climate change through media not traditionally used in the teaching of geochemistry and geophysics.

3. Public engagement: We will also link to Centres, museums, festivals and events to target young people's support networks and bring 'Think Geophysics' to new audiences, specifically the Cambridge Science Festival (an established annual event attracting 25,000); the Annual Big Bang Fair at the The Centre for Life, Newcastle; and the Imperial Festival and Imperial Fringe at Imperial College London and Natural History Museum (Nature Live talks). We will utilize the 'Think' digital presence to enhance learning from the workshops, show real-life applications and associated career pathways. This includes activities for children and parents to continue learning outside of school, resources for teachers, case studies of students studying these subjects and geologists working in the field, and engagement through video, podcasts and social media.

For outreach and public engagement via print and online media, we will work with a freelance science writer who will join one of the two field groups undertaking subglacial bedrock recovery drilling and subsequently report on this aspect of the project, as well as other parts of this project and Thwaites Glacier research generally, in online and print outlets in both the US and UK.

4. The project will support 3 early-career scientists, graduate and undergraduate research at Tulane University, University of Maine, University of Washington, and Imperial College London, and a PhD student hosted at British Antarctic Survey.