Quantifying the Sensitivity of Sea Level Change in Coastal Localities to the Geometry of Polar Ice Mass Flux

Abstract

It has been known for over a century that the melting of individual ice sheets and glaciers drives distinct geographic patterns, or fingerprints, of sea level change, and recent studies have highlighted the implications of this variability for hazard assessment and inferences of meltwater sources. These studies have computed fingerprints using simplified melt geometries; however, a more generalized treatment would be advantageous when assessing or projecting sea level hazards in the face of quickly evolving patterns of ice mass flux. In this paper the usual fingerprint approach is inverted to compute site-specific sensitivity kernels for a global database of coastal localities. These kernels provide a mapping between geographically variable mass flux across each ice sheet and glacier and the associated static sea level change at a given site. Kernels are highlighted for a subset of sites associated with melting from Greenland, Antarctica, and the Alaska–Yukon–British Columbia glacier system. The latter, for example, reveals an underappreciated sensitivity of ongoing and future sea level change along the U.S. West Coast to the geometry of ice mass flux in the region. Finally, the practical utility of these kernels is illustrated by computing sea level predictions at a suite of sites associated with annual variability in Greenland ice mass since 2003 constrained by satellite gravity measurements.

Sea-level fingerprints emergent from GRACE mission data

“…We keep, however, rotational feedback effects of an interannual nature in one set of monthly solutions, and another set of solutions lack these effects. The users of these data should understand the differences, as those employing approaches to using the data to evaluate altimetric time series of order 10 years in length will certainly be interested in using the rotational feedback version for the analysis of interannual trends and variability adjacent to Greenland, for example Müller et al (2019), whereas users focusing on seasonal timescale fingerprints are recommended to employ those coefficients that lack the rotational feedback, as the altimetry and space gravimetry products employed likely have the sea-surface height and gravity effects of the annual polar motion, Chandler wobble, and associated pole tides removed.…”

Antarctic Ice Sheet and emission scenario controls on 21st-century extreme sea-level changes

“…This basin currently shows the largest mass-loss rate 46 and has the potential of ice-sheet instabilities 47,48 . Other nearby regions along the Amundsen Sea Sector are vulnerable as well, but since almost all tide-gauge sites considered in this study are in the far field, small changes in the geometry of the mass loss are unlikely to significantly change the results 49 . Supplementary Fig.…”

Usable Science for Managing the Risks of Sea‐Level Rise

“…The failures of this assumption also has important implications for GRD patterns, which in integrated projections are generally assumed to reflect purely elastic processes and to be constant on centennial timescales. In many cases, integrated projections also do not fully account for changes in the within‐region pattern of mass change (e.g., which parts of Greenland are losing mass), with potential implications for population centers (Larour et al, ; Mitrovica et al, ).…”