The achievability of low-emission IPCC sea-level rise scenarios.

The Intergovernmental Panel on Climate Change (IPCC) AR6 report (2021) provides a range of projections on greenhouse gas emissions and global warming, and the consequential impact on global sea level through thermal expansion of sea water and by glacier and ice-sheet mass loss. This paper assesses the likelihood of lower IPCC sea-level rise scenarios (SSP1-1.9 and SSP1-2.6) in light of current ice-sheet observations and model limitations, alongside today's emissions trends and current shortfall of climate commitments. We conclude that 'low-end' projections may underestimate the true pace and magnitude of future sea-level rise and, if we continue on today's mid-higher emissions pathway (SSP3-7.0), sea-level outcomes of more than 1 m by 2100 should be planned for. The worst can still be avoided through rapid deep emissions reductions, but it is essential that the IPCC continues to reflect these true risks for decision-makers, with rises of more than 2 m this century and several metres thereafter a real possibility. This article is part of the Theo Murphy meeting issue 'Next generation ice-sheet bed measurements'.