Could the Last Interglacial Constrain Projections of Future Antarctic
Ice Mass Loss and Sea-level Rise?
Abstract
Previous studies have interpreted Last Interglacial (LIG;
~129-116 ka) sea-level estimates in multiple different
ways to calibrate projections of future Antarctic ice-sheet (AIS) mass
loss and associated sea-level rise. This study systematically explores
the extent to which LIG constraints could inform future Antarctic
contributions to sea-level rise. We develop a Gaussian process emulator
of an ice-sheet model to produce continuous probabilistic projections of
Antarctic sea-level contributions over the LIG and a future
high-emissions scenario. We use a Bayesian approach conditioning
emulator projections on a set of LIG constraints to find associated
likelihoods of model parameterizations. LIG estimates inform both the
probability of past and future ice-sheet instabilities and projections
of future sea-level rise through 2150. Although best-available LIG
estimates do not meaningfully constrain Antarctic mass loss projections
or physical processes until 2060, they become increasingly informative
over the next 130 years. Uncertainties of up to 50 cm remain in future
projections even if LIG Antarctic mass loss is precisely known (+/-5
cm), indicating there is a limit to how informative the LIG could be for
ice-sheet model future projections. The efficacy of LIG constraints on
Antarctic mass loss also depends on assumptions about the Greenland ice
sheet and LIG sea-level chronology. However, improved field measurements
and understanding of LIG sea levels still have potential to improve
future sea-level projections, highlighting the importance of continued
observational efforts.