With polar temperatures ~2-5°C warmer than today,
the Last Interglacial (LIG) stage serves as a partial analogue
for 1-2°C global warming scenarios. Geological records
from several sites indicate that LIG local sea levels (LSLs)
were higher than today, but because LSLs differ from global sea
level (GSL), accurately reconstructing past GSL requires an
integrated analysis of globally distributed data sets. Here we
present an extensive compilation of LSL indicators and a novel
statistical approach for estimating GSL, LSLs, ice sheet volumes
and their associated uncertainties. We find a 95% probability
that LIG GSL peaked at least 6.6 m higher than today. It likely
(67% probability) exceeded 8.0 m but is unlikely (33%
probability) to have exceeded 9.4 m. When GSL was close to its
current level (>-10 m), the millennial average rate of
GSL rise very likely exceeded 5.6 m/ky but is unlikely to have
exceeded 9.2 m/ky. Our analysis extends previous LIG sea level
studies by integrating literature observations within a
probabilistic framework that accounts for the physics of sea
level change. The results highlight the long-term vulnerability
of ice sheets to even relatively low levels of sustained global
warming.
|
