Communicating projection uncertainty and ambiguity in sea-level assessment
Robert E. Kopp, Michael Oppenheimer, Jessica O’Reilly, Sybren Drijfhout, Tamsin Edwards, Baylor Fox‐Kemper, Gregory G. Garner, Nicholas R. Golledge, Tim H. J. Hermans, Helene T. Hewitt, Benjamin P. Horton, Gerhard Krinner, Dirk Notz, Sophie Nowicki, Matthew D. Palmer, Aimée B. A. Slangen, Cunde Xiao
Abstract
Projections of future sea-level change are characterized by both quantifiable uncertainty and by ambiguity. Both types of uncertainty are relevant to users of sea-level projections, particularly those making long-term investment and planning decisions with multigenerational consequences. Communicating information about both types is thus a central challenge faced by scientists who generate sea-level projections to support decision-making. Diverse approaches to communicating uncertainty in future sea-level projections have been taken over the last several decades, but the literature evaluating these approaches is limited and not systematic. Here, we review how the Intergovernmental Panel on Climate Change (IPCC) has approached uncertainty in sealevel projections in past assessment cycles and how this information has been interpreted by national and subnational assessments, as well as alternative approaches used by recent US subnational assessments. The evidence reviewed here generally supports the explicit approach to communicating both types of uncertainty adopted by the IPCC Sixth Assessment Report (AR6).