Maeve Upton: Statistical Models for sea level change

In 2021, the Intergovernmental Panel on Climate Change (IPCC) released their AR6 report which stated with “high confidence” that the “global mean sea level has increased by 0.2 m between 1901 and 2018”. However, understanding how sea level has varied globally and local, and the main drivers of this change is crucial for predicting future rise. The influence of different sea level drivers, for example thermal expansion, ocean dynamics and glacial – isostatic adjustment (GIA), has changed throughout time and space. Therefore, a useful statistical model requires both flexibility in time and space and have the capability to examine these separate drivers, whilst taking account of uncertainty.

That being said, Maeve Upton is a third year PhD candidate in Maynooth University, developing a series of statistical models to analyse historical sea level and the main drivers of this sea level change. Along with her supervisors Prof Andrew Parnell and Dr Niamh Cahill, Maeve investigates sea level change along the east coast of North America using tide gauge data and proxy records from salt marshes. Her statistical models use Bayesian Hierarchical spatial temporal techniques which can identify changes in sea level in time and across space. Also, the statistical approach uses extensions of Generalised Additive Models (GAMs), which allow separate components of sea level to be modelled individually. The Bayesian framework allows for the inclusion of other physical models to constrain the evolution of sea level change over space and time.

Upton’s models have demonstrated that GIA was the main driver of relative sea level change along North America’s Atlantic coast, until the 20th century when a sharp rise in rates of sea level change can be seen.

In the future work, Upton plans to extended her models to incorporate other drivers of sea level change. Finally, Maeve will collaborate with Earth Scientists in Trinity College Dublin, to produce Ireland’s first historic sea level record from Irish salt marshes and statistical models.