Sea-level projections in recent IPCC reports: how we got here, where we are and where we’re going

Sea-level science has seen many recent developments in observations and modelling of the different contributions and the total mean sea-level change. Here, we focus on sea-level projections in the recent IPCC reports, and discuss (1) the evolution in IPCC projections (“how we got here”), (2) how the projections compare to observations (“where we are”) and (3) the outlook for further improving projections (“where we’re going”). We start by discussing how the model projections of 21st century sea-level change have changed from the IPCC AR5 report (2013) to SROCC (2019) and AR6 (2021), highlighting similarities and differences in the methodologies and comparing the global mean and regional projections. This shows that there is good agreement in the median values, but also highlights some differences. In addition, we discuss how the different reports included high-end projections. We then show how the AR5 projections (from 2007 onwards) compare against the observations, and find that they are highly consistent with each other. Finally, we discuss how to further improve sea-level projections in future studies.