EAR-PF: Detecting dynamic topography in interglacial Caribbean sea level

The warm period ~120,000-years ago was the last time that Earth’s global climate was warmer than the present and is an example of what the Earth might look like in a warmer future. During this time, ice sheets were smaller than today, causing higher mean sea levels. Geologic evidence for higher sea levels includes the fossil coral reefs that make up the Florida Keys, and similar features throughout the Caribbean region and elsewhere.

However, these geologic records indicate that the maximum sea level reached during this warm period was different in different places around the world. This study aims to unravel the various contributing factors to the spatial variability in sea level during this time. In particular, this research seeks to identify the influence of mantle dynamic topography, the deformation of Earth’s surface by the flow of Earth’s mantle, on sea level.

By better constraining the different factors affecting sea level, this research will improve scientists’ understanding of spatial patterns of sea-level change and the sensitivity of ice sheets to climate change. These advances will help scientists better predict future sea levels under a warming climate. More broadly, this research will illuminate the conditions under which the South Florida landscape was formed under shallow marine conditions during the warm period 120,000-years ago, and the risks it faces from ongoing and future sea-level rise.

This project includes an educational component to raise awareness of the geologic history and future climate risks the densely populated Miami region where this research will be performed.

Sea-level rise is a globally pressing concern, but substantial uncertainty exists with both the sensitivity of ice sheets to warming and in the patterns of spatially variable sea-level change. Both components can be constrained by the study of past sea-level change. This project seeks to constrain the influence of mantle dynamic topography on spatio-temporal variations in sea level in the greater Caribbean region during the last interglacial period, ~120,000-years ago.

This was the most recent time that global mean sea level was higher than present, and thus can inform scientists’ understanding of how sea level might change on a future warmer earth. However, past and future sea level are influenced by spatially variable solid earth deformation, including the dynamic topography resulting from mantle flow. To improve scientific understanding of this process, this project will combine numerical modeling with geologic sea-level data.

The first component of the project is the development of high-resolution global models of mantle flow, which predict the magnitude and rate of change of dynamic topography across the greater Caribbean region. The second component is the compilation of a regionally comprehensive dataset of interglacial sea level indicators to reveal spatial trends in sea level across the region.

By combining these data with modeling results and published glacial isostatic adjustment predictions in a statistical inversion, this project will estimate the dynamic topography change and its contribution to spatial variability in sea level across the region and global mean sea level at the last interglacial. These results will improve scientists’ understanding both of spatial variability in sea-level change and of the sensitivity of ice sheets and global mean sea level to changes in climate.

This project also includes a public education campaign to increase awareness of the marine origins of the populous South Florida landscape, formed during the last interglacial period, and of the hazards of sea-level rise in the region.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.