Millennia of sea-level rise awaits: Quantifying spatial uncertainty

Background

Sea-level rise presents one of the greatest environmental challenges for the global community. However, there is deep uncertainty in future projections beyond 2100. This uncertainty increases at higher levels of warming because we may cross thresholds in the Earth’s climate-system which result in rapid irreversible ice loss, potentially causing global sea-level rise of ~15 m by 2300 (IPCC AR6). These eventualities cannot be ruled out and quantification of uncertainties is needed as part of climate risk assessment and coastal decision-making. Current research focuses on global mean sea-level rise until 2300, and not spatially variable, local long-term projections. The palaeo record shows that we are already committed to sea-level rise for millennia due to the long-term response of the ice sheets to warming. This project will seek to explore and quantify the uncertainties of spatially variable sea level on timescales of 100’s to 1000’s of years.

PhD opportunity

Sea-level rise varies in space and time, but projections beyond 2300 simply consider the magnitude of global mean sea level which underplays spatial uncertainties. This PhD project will develop spatially constrained projections of future sea-level rise beyond 2300. Sea-level rise is committed for 1000’s of years and long timeframes are particularly important for infrastructure decision making and global energy security. The timescales of interest will be co-developed in association with the student and Project Partners at the Met Office and wider stakeholders. The UK provides an ideal case study for this work, as future sea-level rise is highly dependent on Antarctic ice melt, as well as the spatial pattern of solid Earth response to palaeo ice sheets.

The project will use machine learning and emulators to explore and quantity the spatial uncertainty of long-term sea-level projections. Emulators are statistical regressions that approximate more complex models to predict changes in climate and sea level, and we have successfully used them to explore spatial uncertainties in ice sheet and sea level rise in the past. The project will build upon this expertise to understand the main drivers of future sea-level rise, under deep uncertainty, using existing simulations to build a range of plausible scenarios of multi-millennial ice sheet evolution to drive a gravitationally consistent sea level model to investigate the patterns and timescale of sea level change around the globe, and regionally around the UK.

This project will take an interdisciplinary approach. A crucial unexplored dimension in climate science is understanding decision-making processes, criteria, uncertainties and trade-offs when decision makers face issues that are beyond human lifetimes. This project will require critically examining decision-making frameworks for their applicability to such contexts. We will work stakeholders to explore these challenges within the framework of sea-level rise.