Infrastructure protectionBetter approach toward projecting, planning for rising sea levels on a warmer Earth

More useful projections of sea level are possible despite substantial uncertainty about the future behavior of massive ice sheets, according to Princeton University researchers.

In two recent papers in the journals Nature Climate Change and the Proceedings of the National Academy of Sciences (PNAS), the researchers present a probabilistic assessment of the Antarctic contribution to twenty-first century sea-level change. A Princeton University release reports that their methodology folds observed changes and models of different complexity into unified projections that can be updated with new information. This approach provides a consistent means to integrate the potential contribution of both continental ice sheets — Greenland and Antarctica — into sea-level rise projections.

“No single ice sheet model or methodology for projections provides sufficient information for good policy and planning decisions,” explained lead author Christopher Little, a postdoctoral research associate in the Program in Science, Technology and Environmental Policy in Princeton’s Woodrow Wilson School of Public and International Affairs.

“Furthermore, there are fundamental limitations in the observational data available on and near ice sheets,” Little said. “Projections of their response to 21st century climate changes are thus very poorly constrained. There’s unlikely to be a single answer in the near future: a better objective is a comprehensive, transparent baseline that can be improved over time.”

The Princeton approach provides a more informative projection of future sea levels that politicians and coastal planners can use to prepare for higher seas, said Little, who works in the group of co-author Michael Oppenheimer, Princeton’s Albert G. Milbank Professor of Geosciences and International Affairs.

Little and Oppenheimer worked on both papers with Nathan Urban, a former postdoctoral researcher with Oppenheimer now at the Los Alamos National Laboratory.

Little explains the findings of both papers as follows:

“Gauging the future rate of sea-level rise is critical for climate-change policy and coastal-planning efforts. One crucial component is the melting of polar ice sheets.

“During the past twenty years, the Greenland and Antarctic ice sheets have lost an increasing amount of ice and now contribute roughly one-third of the rate of global mean sea-level rise. However, the standard tools used to project these ice sheets’ contribution to future sea levels are limited by inadequate process understanding and sparse data. Ice sheets interact with the ocean on small spatial scales, and their motion is strongly governed by poorly understood properties of the ice as well as the sediment hidden several miles beneath