Without Emissions Cuts, A Real Risk of Extreme Sea-level Rise by 2100

Philosophical Transactions of the Royal Society, 23 April 2026

Observations suggest we are currently tracking sea-level rise pathways consistent with intermediate- to high-emission scenarios. These trajectories are already producing rapid increases in the rate of sea-level rise, with some regions, such as the Western Pacific, already experiencing greater increase than the global average. Ice sheet models are unable to adequately capture some processes; as a result, projections may underestimate the true pace and magnitude of future sea-level rise. This study notes that, unless governments put forward actual policies to achieve the lowest emissions scenarios, and given current emissions trends and geopolitical instability, it may be necessary to plan for at least 1 meter of sea-level rise this century. It is therefore essential that the IPCC continue to reflect such extreme risk levels in its seventh assessment cycle (AR7), especially within its Summary for Policy Makers. Higher-end sea levels cannot be ruled out and, indeed, if we continue on such higher emissions pathway, they should be expected. Such an outcome would profoundly change our future world in ways not experienced since the last deglaciation, severely testing international systems not set up to deal with such extremes. The worst can still be avoided through rapid, deep emissions reductions; but decision-makers must begin to fully appreciate that sea-level rise of more than 1 meter and even over 2 meters within this century, and of several meters after that are a real possibility.

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