Climate forcing insufficient to explain sea-level lowstands in Maldives
during Common Era
Abstract
Reconstructions of Common-Era sea level are informative of relationships
between sea level and natural climate variation, and the uniqueness of
modern sea-level rise. Kench et al. recently reconstructed Common-Era
sea level in the Maldives, Indian Ocean, using coral microatolls. They
identified periods of 150-500 yr when sea level fell and rose at average
rates of 2.7-4.3 mm/yr. These periods coincided with intervals of
cooling and warming inferred from proxy reconstructions of sea-surface
temperature (SST) and radiative forcing. Kench et al. reasoned that
these 0.8-0.9-m centennial-scale sea-level fluctuations were driven by
climate, specifically thermal contraction and expansion of seawater. In
contrast to previous studies, Kench et al. argued that modern rates and
magnitudes of sea-level rise caused by climate change have precedent
during the Common Era. We use principles of sea-level physics to argue
that pre-industrial radiative forcing and SST changes were insufficient
to cause thermosteric sea-level (TSL) trends as large as reported for
the Maldives.