EXtreme upper TAil of SEA level rise: constraints from geological records: ExTaSea

Programme(s): H2020-EU.1.3.2. - Nurturing excellence by means of cross-border and cross-sector mobility

Topic(s): MSCA-IF-2018 - Individual Fellowships

Call for proposal: H2020-MSCA-IF-2018

Funding Scheme: MSCA-IF-EF-ST - Standard EF

Grant agreement ID: 838841

Project description

Predicting tomorrow's sea levels today

A major threat that may emerge as a consequence of global warming is the increased risk of coastal floods from extreme sea levels (ESLs). Reliable assessments of sea level variability, including ESLs, are crucial for developing coastal defence and adaptation strategies. Future sea level rise projections are poorly described and unreliable because of the lack of understanding of the dynamics and responses of the Greenland and Antarctic ice sheets to a warming world. The EU-funded ExTaSea project will address the ambiguities that exist in current sea level projections using geological data that are useful analogues for the future, and statistical techniques, to produce policy-relevant extreme sea-level scenarios that capture the natural bounds of sea level change.

Objective

Sea-level rise is a major societal concern, with potential impacts on population, infrastructure and coastal environments. Coastal defence and adaptation strategies are highly dependent upon our ability to understand and predict sea-level variability, including extreme sea levels. Quantifying the upper tail probability of sea level – i.e. the risk of extremes - is therefore of high socio-economic relevance. Current projections suggest a low probability of polar ice-sheet decay scenarios, but they cannot be ruled out. Such scenarios are poorly parameterized and/or associated with large uncertainties in current projections. The ExTaSea project will address two sources of uncertainty in current projections of future sea-level: (1) our understanding of the system and, (2) the degree to which we can simulate natural variability. ExTaSea will do this by producing well quantified natural bounds on both the rate and magnitude of sea level rise (objective 1) and probability distributions that include specific information on high-end extremes for global mean and regional sea levels (objective 2). These will contribute to our understanding of these sources of uncertainty and will form the basis for policy-relevant extreme sea-level scenarios (objective 3) that account for the dynamic response of the ice sheets to climate forcing. ExTaSea will produce statistical distributions by: (1) collating and quality checking already available geological data from past time intervals of the last 200,000 years that are useful analogues for future change; (2) novel statistical techniques (e.g. modified Bayesian partition modelling) and (3) modelling of solid Earth deformation processes (GIA) that will allow absolute magnitudes of sea levels to be determined. As the geological record integrates all processes, the statistical distributions on the natural bounds of sea-level will include the high-impact (extreme) tail associated with mass loss from the polar ice sheets.