Future Sea Level Rise Projected to be Double that of Previous Estimates

Rising sea levels pose a serious threat to coastal ecosystems and communities living in coastal areas all around the world. Yet, in order to accurately project future sea level rise (SLR) one first needs to accurately project the contribution of melting ice sheets, which is challenging using conventional modeling methods. Climate change adaptation strategies that focus on SLR urgently need to quantify future uncertainties, especially uncertainties pertaining to upper-end estimates.

A new approach, known as structured expert judgement (SEJ) has been used successfully to address similar problems that are not easily solved with models. Now, a team of researchers have applied this approach to more accurately estimate future SLR based on the input of experts who have an in-depth knowledge of the contribution of Greenland and Antarctic melting ice sheets.

The findings, which included input from 22 experts on the Greenland and Antarctic ice sheets, was recently published in the Proceedings of the National Academy of Sciences.

The experts provided feasible ranges for several variables, including future ice accumulation, discharge, and surface runoff, as well as how much these variables were dependent on each other, for the Greenland, East Antarctic and West Antarctic ice sheets, under both a low and high rise in global temperatures. The authors then used these results to project future global SLR under various temperature rise scenarios.

How much will Melting Ice Sheets Contribute to Future Sea Level Rise?

They found there is a small, yet significant, probability that SLR could exceed 2 meters by 2100 under a high-temperature scenario (business as usual), which is more than double the upper value presented by the Intergovernmental Panel on Climate Change's Fifth Assessment Report.

According to the study, a 2 meter increase in SLR could result in 1,79 million square kilometers of land being lost, including regions critical for food production, and could cause up to 187 million people to be displaced. It is clear a rise in sea levels of this magnitude would have far-reaching consequences for humankind. We therefore need to make a concerted effort to reduce our emissions in order to curb rising global temperatures, and it is important coastal communities consider the potential for SLR to exceed 2m by 2100 when planning and implementing their climate adaptation strategies.

Journal Reference

Jonathan L. Bamber, Michael Oppenheimer, Robert E. Kopp, Willy P. Aspinall, and Roger M. Cooke. Ice sheet contributions to future sea-level rise from structured expert judgment. PNAS. (2019) doi.org/10.1073/pnas.1817205116

Featured Image by Christine Zenino [CC BY 2.0], via Wikimedia Commons