Increased ice loading in the Antarctic Peninsula since the 1850s and its effect on glacial isostatic adjustment

Antarctic Peninsula (AP) ice core records indicate significant accumulation increase since 1855, and any resultant ice mass increase has the potential to contribute substantially to present-day glacial isostatic adjustment (GIA). We derive empirical orthogonal functions from climate model output to infer typical spatial patterns of accumulation over the AP and, by combining with ice core records, estimate annual accumulation for the period 1855-2010. In response to this accumulation history, high resolution ice-sheet modeling predicts ice thickness increases of up to 45 m, with the greatest thickening in the northern and western AP. Whilst this thickening is predicted to affect GRACE estimates by no more than 6.2 Gt/yr, it may contribute up to -7 mm/yr to the present-day GIA uplift rate, depending on the chosen Earth model, with a strong east-west gradient across the AP. Its consideration is therefore critical to the interpretation of observed GPS velocities in the AP