Abstract. The emphasis for informing policy makers on future
sea-level rise has been on projections by the end of the 21st century.
However, due to the long lifetime of atmospheric CO2, the thermal
inertia of the climate system and the slow equilibration of the ice sheets,
global sea level will continue to rise on a multi-millennial timescale even
when anthropogenic CO2 emissions cease completely during the coming
decades to centuries. Here we present global sea-level change projections
due to the melting of land ice combined with steric sea effects during the next
10 000 years calculated in a fully interactive way with the Earth system
model of intermediate complexity LOVECLIMv1.3. The greenhouse forcing is
based on the Extended Concentration Pathways defined until 2300 CE with no
carbon dioxide emissions thereafter, equivalent to a cumulative CO2
release of between 460 and 5300 GtC. We performed one additional experiment
for the highest-forcing scenario with the inclusion of a methane emission
feedback where methane is slowly released due to a strong increase in
surface and oceanic temperatures. After 10 000 years, the sea-level change
rate drops below 0.05 m per century and a semi-equilibrated state is
reached. The Greenland ice sheet is found to nearly disappear for all
forcing scenarios. The Antarctic ice sheet contributes only about 1.6 m to
sea level for the lowest forcing scenario with a limited retreat of the
grounding line in West Antarctica. For the higher-forcing scenarios, the
marine basins of the East Antarctic Ice Sheet also become ice free,
resulting in a sea-level rise of up to 27 m. The global mean sea-level
change after 10 000 years ranges from 9.2 to more than 37 m. For the
highest-forcing scenario, the model uncertainty does not exclude the complete
melting of the Antarctic ice sheet during the next 10 000 years.
Semi-equilibrated global sea-level change projections for the next 10 000 years