Positive Late 20th-century Trend in Antarctic Snow Accumulation Drives
Modest Mitigation of Sea Level Rise
Abstract
Increasing snow accumulation over the Antarctic Ice Sheet may mitigate
future sea level rise. However, current estimates of mitigation
potential are poorly constrained due to limited records of past
variability. We present an annually resolved reconstruction of Antarctic
snow accumulation from 1801 to 2000 CE, employing a paleoclimate data
assimilation methodology to integrate ice core records with a
multi-model ensemble of climate simulations. Our reconstruction
correlates well with instrumental reanalysis, and we find that Antarctic
accumulation rates increased over the 20th-century, resulting in a
modest amount (~1 mm) of sea level mitigation.
Mitigation is primarily driven by an accelerating trend since around
1970. Our results contrast with a previous mitigation estimate of
~10 mm; this discrepancy is due to unconstrained
baseline estimates of 19th-century accumulation in East Antarctica. Our
reconstruction suggests that the uncertainty of future sea level
mitigation from increasing Antarctic accumulation has been
underestimated.