Periodic Reporting for period 2 - INCISED (Interglacial Collapse of Ice Sheets revealed by Subglacial Drilling of Bedrock)
Okres sprawozdawczy: 2022-03-01 do 2023-08-31
INCISED is an innovative approach to a long-standing scientific problem. The question is if the West Antarctic Ice Sheet has collapsed in the recent geological past (last few 100,000 years) and if so when. INCISED has developed new technology and adapted existing technology to allow us to retrieve samples of bedrock from holes we will drill hundreds of metres under the ice sheet. By analysing these rock samples we will be able to determine when the ice sheet last collapsed. We will simultaneously use ice sheet models to determine what climate conditions might have led to such ice sheet collapse.
The possible future collapse of the West Antarctic Ice Sheet is an important tipping point that sea level projections have to try to account for. The work will help us provide more robust projections of future sea level which is important for policymakers as we plan for future sea level rise.
Specific Objectives
There is a series of seven objectives that form a logical workflow of drilling for bedrock samples, cosmogenic isotope analysis to determine past WAIS collapse states, and finally modelling to determine ice sheet volume and to explore forcing factors. INCISED will be divided into 4 main workpackages to deliver these objectives
Test and pilot study workpackage
O1. Test and refine a previously-developed rock drill in a range of environments including laboratory, cold store, and on a range of lithologies, followed by work at a carefully-targetted field test site.
Main Drilling workpackage
O2. Identify a range of sites in West Antarctica where ice sheet thickness responds sensitively to super-interglacials (partial or full collapse of WAIS)
O3. Retrieve bedrock cores from progressively deeper drill holes along transects at each of sites in O2
Analysis and Interpretation workpackage
O4. Analyse the bedrock samples for a range of cosmogenic isotopes and use these to test hypotheses of WAIS collapse (exposure-burial histories)
O5. Use 3-D ice sheet models to translate former ice surface levels to ranges of possible WAIS volume change and therefore sea-level rise associated with each super-interglacial collapse event
O6. Bring together published datasets to explore and, where possible quantify, forcing conditions at the time of collapse events in O4.
Synthesis and Write-up workpackage
O7. Synthesise O5-O6 to achieve the aim of demonstrating direct and dated evidence for past WAIS collapse events, quantify the associated sea-level rise, and forcing conditions associated with collapse.
The possible future collapse of the West Antarctic Ice Sheet is an important tipping point that sea level projections have to try to account for. The work will help us provide more robust projections of future sea level which is important for policymakers as we plan for future sea level rise.
Specific Objectives
There is a series of seven objectives that form a logical workflow of drilling for bedrock samples, cosmogenic isotope analysis to determine past WAIS collapse states, and finally modelling to determine ice sheet volume and to explore forcing factors. INCISED will be divided into 4 main workpackages to deliver these objectives
Test and pilot study workpackage
O1. Test and refine a previously-developed rock drill in a range of environments including laboratory, cold store, and on a range of lithologies, followed by work at a carefully-targetted field test site.
Main Drilling workpackage
O2. Identify a range of sites in West Antarctica where ice sheet thickness responds sensitively to super-interglacials (partial or full collapse of WAIS)
O3. Retrieve bedrock cores from progressively deeper drill holes along transects at each of sites in O2
Analysis and Interpretation workpackage
O4. Analyse the bedrock samples for a range of cosmogenic isotopes and use these to test hypotheses of WAIS collapse (exposure-burial histories)
O5. Use 3-D ice sheet models to translate former ice surface levels to ranges of possible WAIS volume change and therefore sea-level rise associated with each super-interglacial collapse event
O6. Bring together published datasets to explore and, where possible quantify, forcing conditions at the time of collapse events in O4.
Synthesis and Write-up workpackage
O7. Synthesise O5-O6 to achieve the aim of demonstrating direct and dated evidence for past WAIS collapse events, quantify the associated sea-level rise, and forcing conditions associated with collapse.
So far INCISED has partly addressed Objectives 1 and 2.
Specifically we have built and refined the innovate new rock drill, along with the associated ice drill needed to access the bed beneath the ice sheet.
Refinements to the drill have included features to de-risk the operation of the drill, such as higher specification motors adapted to the challenging conditions of subglacial access, and refinements to maximise the retrieval of sample volume.
COVID impacts have led to delays in the drill and in testing it but we have now partly tested the drill in some cold conditions.
We have successfully undertaken a survey of multiple potential drill sites in West Antarctica. This was achieved with a sophisticated sled-mounted radar system that allowed us to map the ice sheet bed in our survey areas in good detail, and thus to select target drill sites for our full drill seasons in Objective 3. We hus have target sites with reasonably flat bed and where we have made an evaluation of local geology.
We have presented the ongoing and planned work at conferences and workshops, where there is significant interest in subglacial drilling.
Specifically we have built and refined the innovate new rock drill, along with the associated ice drill needed to access the bed beneath the ice sheet.
Refinements to the drill have included features to de-risk the operation of the drill, such as higher specification motors adapted to the challenging conditions of subglacial access, and refinements to maximise the retrieval of sample volume.
COVID impacts have led to delays in the drill and in testing it but we have now partly tested the drill in some cold conditions.
We have successfully undertaken a survey of multiple potential drill sites in West Antarctica. This was achieved with a sophisticated sled-mounted radar system that allowed us to map the ice sheet bed in our survey areas in good detail, and thus to select target drill sites for our full drill seasons in Objective 3. We hus have target sites with reasonably flat bed and where we have made an evaluation of local geology.
We have presented the ongoing and planned work at conferences and workshops, where there is significant interest in subglacial drilling.
INCISED by its nature is a project where key scientific results will be back-loaded towards the latter stages of the project. After significant COVID delays we are now ready for a full field test of the drill and then to retrieve bedrock samples from under the West Antarctic Ice Sheet as part of Objective 3. This will be followed by cosmogenic analysis of samples (O4) and numerical modelling of past ice sheet behaviour (O5), before we synthesise the results (O6). Given the delays, we are planning a slightly different sequencing of some of the work in order to try and catch up some time.