A new way to predict future sea levels

Posted by Flora Malein

A new method for predicting future sea levels that mathematically pools expert predictions is being used by climate scientists.

The new method known as ‘structured expert elicitation’ (EE) is already used in other areas of science such as forecasting volcano eruptions and the spread of diseases. A new report published in Nature Climate Change highlights how EE can be used to make predictions about how much ice sheets are likely to melt; an area of great uncertainty in trying to understand how much sea levels are going to rise in the future.
 
Jonathan Bamber and Willy Aspinal, scientists from the University of Bristol UK, used EE to collect detailed evidence from 26 experts on their understanding of the key processes, climate drivers and the long and short-term future of the ice sheets. After repeating the questionnaire two years later to improve accuracy, they then used mathematical modeling to pool the responses of the experts.
 
Bamber and Aspinal found that glacial melt was predicted to contribute to an average 29cm sea level rise by 2100. There was also a 5 percent probability that it would exceed 84cm.  When these predictions were added to other sources of sea level rise, they suggest that we are at risk of seeing a greater sea level rise than 1m by 2100.
 
"This is the first study of its kind on ice sheet melting to use a formalized mathematical pooling of experts’ opinions," says Bamber who is a professor in glaciology.
 
"It demonstrates the value and potential of this approach for a wide range of similar problems in climate change research, where past data and current numerical modeling have significant limitations when it comes to forecasting future trends and patterns."
 
The study also found that the scientists were uncertain about what was responsible for the recent losses from ice sheets and whether these are a short or long-term trend. They hope that the new method should could throw some much needed light on predictions surrounding future sea-levels