Long-term contributions of Baffin and Bylot Island Glaciers to sea level rise: an integrated approach using airborne and satellite laser altimetry, stereoscopic imagery and satellite gravimetry

Abstract

Canadian Arctic glaciers have recently contributed large volumes of meltwater to the world's oceans. To place recently observed glacier wastage into a historical perspective and to determine the region's longer-term (~50 years) contribution to sea level, we estimate mass and volume changes for the glaciers of Baffin and Bylot Islands using Digital Elevation Models generated from airborne and satellite stereoscopic imagery and elevation postings from repeat airborne and satellite laser altimetry. In addition, we update existing glacier mass change records from GRACE satellite gravimetry to cover the period from 2003 to 2011. Using an integrated approach we find that the rate of mass loss from the region's glaciers increased from 11.1 ± 1.8 Gt a<sup>−1</sup> (–270 ± 40 kg m<sup>−2</sup> a<sup>−1</sup>) in 1963–2006 to 23.8 ± 3.1 Gt a<sup>−1</sup> (–580 ± 80 kg m<sup>2</sup> a<sup>−1</sup>) in 2003–2011. The doubling of the rate of mass loss is attributed to higher temperatures in summer with little change in annual precipitation. Through both direct and indirect effects, changes in summer temperatures accounted for 68–98 % of the variance in the rate of mass loss to which the Barnes Ice Cap was found to be 1.6 times more sensitive than either the Penny Ice Cap or the regions glaciers as a whole. Between 2003 and 2011 the glaciers of Baffin and Bylot Islands contributed 0.07 ± 0.01 mm a<sup>−1</sup> to sea level rise, a rate equivalent to the contribution coming from Patagonian glaciers. Over the 48-year period between 1963 and 2011 the glaciers of Baffin and Bylot Islands contributed 1.7 mm to the world's oceans

Satellite-derived volume loss rates and glacier speeds for the Cordillera Darwin Icefield, Chile

“…Assuming that firn (600 kg m −3 ) is lost in the accumulation zone and ice (900 kg m −3 ) is lost in the ablation zone (considered as a possible scenario by Kääb et al, 2012) reduces the mass change rate by 0.3 Gt yr −1 . Assuming an ice density of 900 ± 25 kg m −3 (e.g., Gardner et al, 2012) adds ±0.1 Gt yr −1 to our uncertainty. The effect of density changes are small (∼ 10 %) as most of the mass loss occurs from ice in the ablation zone.…”

GRACE, time-varying gravity, Earth system dynamics and climate change

“…22), mainly due to increased melt in response to higher air temperatures. About two-third of the ice loss (39±9 Gt/yr) was attributed to the northern part of the archipelago, while in the southern part, the melt (24±7 Gt/yr) was found to have doubled compared to its longterm value (11.1±1.8 Gt/yr for 1963-2008 [234]). Recently, GRACE data was also used to validate climate projections of a more advanced regional climate model in the CAA region, which indicates that the accelerated ice-mass loss will be sustained in the 21 st century [235].…”