Surface Mass Balance Variability Causes Viscoelastic Solid Earth Deformation in the Antarctic Peninsula

Abstract Present‐day ice‐mass changes in Antarctica typically deform the solid Earth elastically, and this signal needs removing from Global Positioning System (GPS) observations of displacement before they can be used to constrain models of glacial isostatic adjustment. However, much of West Antarctica is underlain by weak upper mantle, meaning these short‐term fluctuations may also cause viscous (transient or steady‐state) deformation of the Earth. We model the viscoelastic response of the Earth to surface mass balance (SMB) variability in the Antarctic Peninsula and find an improved fit to GPS data at most sites compared to elastic only. Viscoelastic modeling constrains upper mantle steady‐state viscosity in the northern Peninsula to 5 × 10 17 to 2 × 10 18 Pa s, and >1 × 10 18 Pa s for the mid to southern Peninsula. In the northern Peninsula, removing viscoelastic displacement caused by SMB variability from GPS time series increases estimated uplift rates by up to 3 mm/yr compared with using an elastic‐only correction.