Emerging threatsPutting consistent value on experts' uncertainty on climate change models

Published 29 April 2016

Science can flourish when experts disagree, but in the governmental realm uncertainty can lead to inadequate policy and preparedness. When it comes to climate change, it can be OK for computational models to differ on what future sea levels will be. The same flexibility does not exist for determining the height of a seawall needed to protect people from devastating floods. For the first time in the climate field, researchers have combined two techniques long used in fields where uncertainty is coupled with a crucial need for accurate risk-assessment — such as nuclear energy — in order to bridge the gap between projections of Earth’s future climate and the need to prepare for it.

Science can flourish when experts disagree, but in the governmental realm uncertainty can lead to inadequate policy and preparedness. When it comes to climate change, it can be OK for computational models to differ on what future sea levels will be. The same flexibility does not exist for determining the height of a seawall needed to protect people from devastating floods.

Princeton U reports that for the first time in the climate field, a Princeton University researcher and collaborators have combined two techniques long used in fields where uncertainty is coupled with a crucial need for accurate risk-assessment — such as nuclear energy — in order to bridge the gap between projections of Earth’s future climate and the need to prepare for it. Reported in the journal Nature Climate Change, the resulting method consolidates climate models and the range of opinions that leading scientists have about them into a single, consistent set of probabilities for future sea-level rise.

Scientists working in climate change know that the models used throughout climate research have shortcomings. At the same time policymakers need to know the future of sea-level rise, and they need as robust a prediction as we can give,” said Michael Oppenheimer, Princeton’s Albert G. Milbank Professor of Geosciences and International Affairs and the Princeton Environmental Institute and first author of the paper.

For someone trying to prepare their city or coastline, how much the ocean will rise is not an abstract question,” Oppenheimer said. “They need a number that’s not too high or too low. Lives and dollars are at risk.”

Climate projections attempt to capture immense, complicated phenomena that are dependent on various shifting factors — natural and man-made — and complex interactions between oceans, ice and land. Ice in particular is “notoriously difficult” to model, Oppenheimer said. Giving statistically accurate and informative assessments of a model’s uncertainty is a daunting task, and an expert’s scientific training for such an estimation may not always be adequate.