Surface Elevation Changes Over the Past Decade Across Penny Ice Cap, Baffin Island, Canada

Geodetic methods have been relied on heavily to quantify the response of glaciers and ice caps to warmingover the past few decades (e.g. Abdalati et al., 2004; Gardner et al., 2011; Gardner et al., 2012). Typicallyin such studies, the observed surface elevation change of a glacier or ice cap over a given time interval is used to directly calculate its mass loss. However, there can be a change elevation due to a change in firndensification rate or ice dynamics without actual mass loss. For example, at the summit of Penny Ice Cap,Baffin Island, the firn density increased due to the formation of infiltration ice layers, resulting in a 6%increase in cumulative ice‐equivalent thickness between 1995 and 2010 (Zdanowicz et al., 2012).To our knowledge no studies have previously measured the vertical component of ice motion (firncompaction and/or ice dynamics) or adjusted geodetic data over an entire ice cap in the Canadian Arctic. Inthis study we use NASA Airborne Topographic Mapper (ATM) laser altimetry data, ICESat data, as well as insitu geodetic and surface mass balance measurements, to determine surface elevation changes over Penny Ice Cap from 2005‐2013, and correct these data to account for the effects of vertical motion due to ice dynamics and firn densification. Our results show that failure to account for vertical ice motion and firn densification would result in an~19% overestimation of mass loss for this ice cap.