Overview

Project Highlights:

  • Use cutting-edge modelling techniques to improve understanding of Earth's warm past
  • Inform one of the most uncertain and important parts of climate change, the Antarctic ice sheet contribution to sea level
  • Make a vital contribution to climate science, feeding into the next Intergovernmental Panel on Climate Change (IPCC) report

Sea level rise has been described as the 'single greatest threat of climate change', increasing coastal flood frequency and severity for a growing coastal population: up to 1.4 billion people are predicted to live within 10 m of sea level by 2060. This project aims to learn from a time in the Earth's past when sea levels were high to improve predictions of the future.

During the mid-Pliocene period, 3 million years ago, sea level was many metres higher even though atmospheric CO2 concentrations were at current levels (around 400 ppm) and global mean temperatures were within the range predicted for this century (2-3 °C warmer). Estimates range from around 6 m to 27 m higher sea level than present, with the uncertainty arising from the size of the Antarctic ice sheet (Fig. 1 shows one estimate). This high mid-Pliocene sea level may have important implications for predictions of sea level rise this century, for which Antarctica is also the most uncertain part.

Recently1 an Antarctic ice sheet model tested by its agreement with reconstructed Pliocene sea level predicted the sea level contribution could exceed 1 m by 2100, roughly doubling predictions for total sea level rise from the Intergovernmental Panel on Climate Change. In contrast, a different Antarctic ice sheet model tested by its agreement with recent satellite data2 predicted only around a 10 cm contribution by 2100. The reasons for this order of magnitude difference are not yet clear but may include the use of Pliocene versus modern data to test the models, the inclusion of a hypothetical mechanism for rapid ice loss1, or methodological choices in model testing and prediction. Understanding the behaviour of the Pliocene ice sheet is a key part of assessing the potential for rapid sea level rise this century, and therefore of society adapting to climate change.

The project aims to quantify Antarctic contribution to sea level during the mid-Pliocene, and the rate at which it occurred, to improve predictions of future sea level rise. The project will use the state-of-the-art ice sheet model BISICLES3 to run a suite ('ensemble') of simulations exploring a range of factors that control Pliocene changes. This is an exciting opportunity because BISICLES has not been used to study this era before. Some of the factors will be specific to the Pliocene, such as atmosphere and ocean changes, and some to the model, such as physical processes and parameters. Understanding which of these drive rapid sea level rise will help with understanding the risk of similar rates occurring in future. The simulations will also be evaluated with existing Pliocene sea level reconstructions. The evaluation will be novel compared with previous work1 by using statistical techniques for the comparison2 and investigating the possibility of using rates of change as well as total sea level rise.

The project will inform the Intergovernmental Panel on Climate Change Sixth Assessment Report for policy makers. Results on how BISICLES behaves under climate change and modelling uncertainties will be fed into the IPCC report, providing key evidence for predicting future sea level rise.

Reconstructed mid-Pliocene Antarctic terrain and ice sheet elevation (Source: PRISM project).

Methodology

BISICLES is very computationally expensive (because it uses high spatial resolution at the edge of the ice sheet), so it is not possible to explore every possible scenario. Instead, a subset of scenarios will be simulated and statistical modelling used to quantify how the results depend on different factors. The statistical model ('emulator') can then be used as a fast replacement for BISICLES to simulate any possible scenario and assess the sensitivity of ice losses to different factors. The results will be compared with a range of available mid-Pliocene reconstructions.

Training and Skills

The student will receive training in using the numerical ice sheet model BISICLES, statistical modelling, and other computing and data analysis methods required for the project. All are widely applicable in other scientific and technical areas.

CENTA students are required to complete 45 days training throughout their PhD including a 10 day placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skills sets to master classes specific to CENTA research themes. 

Timeline

Year 1: Performing test simulations and constructing initial emulator. Attending Karthaus glaciology summer school (Italy) and BISICLES or statistics training course.  Visiting L. Gregoire in Leeds.

Year 2: Running ensemble of BISICLES simulations and refining emulator. Presenting at EGU conference in Vienna. Visiting L. Gregoire.

Year 3: Comparing simulations with palaeodata and reviewing implications for future sea level rise. Presenting at “Uncertainty in Computer Models” and UK glaciology meeting. Visiting L. Gregoire.

Partners and collaboration (including CASE)

Project partner Dr Tina van de Flierdt (Imperial College London) will provide expertise and data for Pliocene sea level reconstructions. Possible case partners: British Antarctic Survey, British Geological Survey.

Further Details

Students should have an undergraduate degree in or closely related to physics, mathematics or geophysics, and an enthusiasm for quantifying uncertainties in future climate impacts. Experience in programming and/or applied statistics would be an advantage but is not essential. Interested candidates are encouraged to contact Tamsin Edwards (tamsin.edwards@open.ac.uk) for more information. 

Applications should include:

Apologies that some bits of information are requested multiple times on different forms. Please fill in everything requested.

Applications should be sent to

STEM-EEES-PhD-Student-Recruitment@open.ac.uk  

by 5 pm on 25th January 2017